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annotate test/testshader.c @ 5237:74bc160186a8

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Added a simple GLSL example using SDL
author Sam Lantinga <slouken@libsdl.org>
date Tue, 08 Feb 2011 22:11:16 -0800
parents
children c7be6ca3a0b8
rev   line source
5237
74bc160186a8 Added a simple GLSL example using SDL
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1 /* This is a simple example of using GLSL shaders with SDL */
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2
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3 #include "SDL.h"
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4
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5 #ifdef HAVE_OPENGL
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6
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7 #include "SDL_opengl.h"
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8
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9
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10 static SDL_bool shaders_supported;
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11 static int current_shader = 0;
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12
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13 enum {
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14 SHADER_COLOR,
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15 SHADER_TEXTURE,
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16 SHADER_TEXCOORDS,
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17 NUM_SHADERS
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18 };
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19
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20 typedef struct {
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21 GLuint program;
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22 GLuint vert_shader;
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23 GLuint frag_shader;
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24 const char *vert_source;
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25 const char *frag_source;
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26 } ShaderData;
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27
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28 static ShaderData shaders[NUM_SHADERS] = {
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29
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30 /* SHADER_COLOR */
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31 { 0, 0, 0,
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32 /* vertex shader */
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33 "varying vec4 v_color;\n"
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34 "\n"
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35 "void main()\n"
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36 "{\n"
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37 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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38 " v_color = gl_Color;\n"
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39 "}",
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40 /* fragment shader */
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41 "varying vec4 v_color;\n"
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42 "\n"
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43 "void main()\n"
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44 "{\n"
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45 " gl_FragColor = v_color;\n"
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46 "}"
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47 },
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48
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49 /* SHADER_TEXTURE */
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50 { 0, 0, 0,
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51 /* vertex shader */
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52 "varying vec4 v_color;\n"
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53 "varying vec2 v_texCoord;\n"
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54 "\n"
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55 "void main()\n"
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56 "{\n"
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57 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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58 " v_color = gl_Color;\n"
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59 " v_texCoord = vec2(gl_MultiTexCoord0);\n"
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60 "}",
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61 /* fragment shader */
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62 "varying vec4 v_color;\n"
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63 "varying vec2 v_texCoord;\n"
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64 "uniform sampler2D tex0;\n"
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65 "\n"
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66 "void main()\n"
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67 "{\n"
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68 " gl_FragColor = texture2D(tex0, v_texCoord) * v_color;\n"
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69 "}"
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70 },
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71
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72 /* SHADER_TEXCOORDS */
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73 { 0, 0, 0,
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74 /* vertex shader */
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75 "varying vec2 v_texCoord;\n"
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76 "\n"
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77 "void main()\n"
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78 "{\n"
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79 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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80 " v_texCoord = vec2(gl_MultiTexCoord0);\n"
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81 "}",
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82 /* fragment shader */
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83 "varying vec2 v_texCoord;\n"
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84 "\n"
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85 "void main()\n"
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86 "{\n"
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87 " vec4 color;\n"
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88 " vec2 delta;\n"
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89 " float dist;\n"
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90 "\n"
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91 " delta = vec2(0.5, 0.5) - v_texCoord;\n"
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92 " dist = dot(delta, delta);\n"
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93 "\n"
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94 " color.r = v_texCoord.x;\n"
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95 " color.g = v_texCoord.x * v_texCoord.y;\n"
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96 " color.b = v_texCoord.y;\n"
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97 " color.a = 1.0 - (dist * 4.0);\n"
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98 " gl_FragColor = color;\n"
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99 "}"
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100 },
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101 };
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102
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103 static PFNGLATTACHOBJECTARBPROC glAttachObjectARB;
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104 static PFNGLCOMPILESHADERARBPROC glCompileShaderARB;
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105 static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB;
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106 static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB;
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107 static PFNGLDELETEOBJECTARBPROC glDeleteObjectARB;
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108 static PFNGLGETINFOLOGARBPROC glGetInfoLogARB;
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109 static PFNGLGETOBJECTPARAMETERIVARBPROC glGetObjectParameterivARB;
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110 static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB;
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111 static PFNGLLINKPROGRAMARBPROC glLinkProgramARB;
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112 static PFNGLSHADERSOURCEARBPROC glShaderSourceARB;
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113 static PFNGLUNIFORM1IARBPROC glUniform1iARB;
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114 static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB;
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115
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116 static SDL_bool CompileShader(GLenum shader, const char *source)
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117 {
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118 GLint status;
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119
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120 glShaderSourceARB(shader, 1, &source, NULL);
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121 glCompileShaderARB(shader);
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122 glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status);
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123 if (status == 0) {
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124 GLint length;
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125 char *info;
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126
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127 glGetObjectParameterivARB(shader, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length);
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128 info = SDL_stack_alloc(char, length+1);
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129 glGetInfoLogARB(shader, length, NULL, info);
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130 fprintf(stderr, "Failed to compile shader:\n%s\n%s", source, info);
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131 SDL_stack_free(info);
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132
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133 return SDL_FALSE;
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134 } else {
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135 return SDL_TRUE;
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136 }
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137 }
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138
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139 static SDL_bool CompileShaderProgram(ShaderData *data)
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140 {
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141 const int num_tmus_bound = 4;
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142 int i;
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143 GLint location;
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144
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145 glGetError();
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146
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147 /* Create one program object to rule them all */
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148 data->program = glCreateProgramObjectARB();
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149
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150 /* Create the vertex shader */
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151 data->vert_shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
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152 if (!CompileShader(data->vert_shader, data->vert_source)) {
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153 return SDL_FALSE;
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154 }
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155
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156 /* Create the fragment shader */
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157 data->frag_shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
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158 if (!CompileShader(data->frag_shader, data->frag_source)) {
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diff changeset
159 return SDL_FALSE;
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160 }
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161
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diff changeset
162 /* ... and in the darkness bind them */
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163 glAttachObjectARB(data->program, data->vert_shader);
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164 glAttachObjectARB(data->program, data->frag_shader);
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165 glLinkProgramARB(data->program);
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166
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diff changeset
167 /* Set up some uniform variables */
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168 glUseProgramObjectARB(data->program);
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169 for (i = 0; i < num_tmus_bound; ++i) {
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170 char tex_name[5];
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171 SDL_snprintf(tex_name, SDL_arraysize(tex_name), "tex%d", i);
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172 location = glGetUniformLocationARB(data->program, tex_name);
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173 if (location >= 0) {
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174 glUniform1iARB(location, i);
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175 }
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176 }
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177 glUseProgramObjectARB(0);
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178
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179 return (glGetError() == GL_NO_ERROR);
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180 }
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181
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182 static void DestroyShaderProgram(ShaderData *data)
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183 {
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184 glDeleteObjectARB(data->vert_shader);
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185 glDeleteObjectARB(data->frag_shader);
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186 glDeleteObjectARB(data->program);
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187 }
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188
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189 static SDL_bool InitShaders()
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190 {
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191 int i;
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192
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193 /* Check for shader support */
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194 shaders_supported = SDL_FALSE;
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195 if (SDL_GL_ExtensionSupported("GL_ARB_shader_objects") &&
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196 SDL_GL_ExtensionSupported("GL_ARB_shading_language_100") &&
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197 SDL_GL_ExtensionSupported("GL_ARB_vertex_shader") &&
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198 SDL_GL_ExtensionSupported("GL_ARB_fragment_shader")) {
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199 glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC) SDL_GL_GetProcAddress("glAttachObjectARB");
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200 glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC) SDL_GL_GetProcAddress("glCompileShaderARB");
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201 glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glCreateProgramObjectARB");
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202 glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC) SDL_GL_GetProcAddress("glCreateShaderObjectARB");
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203 glDeleteObjectARB = (PFNGLDELETEOBJECTARBPROC) SDL_GL_GetProcAddress("glDeleteObjectARB");
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204 glGetInfoLogARB = (PFNGLGETINFOLOGARBPROC) SDL_GL_GetProcAddress("glGetInfoLogARB");
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205 glGetObjectParameterivARB = (PFNGLGETOBJECTPARAMETERIVARBPROC) SDL_GL_GetProcAddress("glGetObjectParameterivARB");
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206 glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) SDL_GL_GetProcAddress("glGetUniformLocationARB");
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207 glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) SDL_GL_GetProcAddress("glLinkProgramARB");
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208 glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC) SDL_GL_GetProcAddress("glShaderSourceARB");
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209 glUniform1iARB = (PFNGLUNIFORM1IARBPROC) SDL_GL_GetProcAddress("glUniform1iARB");
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210 glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glUseProgramObjectARB");
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211 if (glAttachObjectARB &&
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212 glCompileShaderARB &&
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213 glCreateProgramObjectARB &&
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214 glCreateShaderObjectARB &&
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215 glDeleteObjectARB &&
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216 glGetInfoLogARB &&
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217 glGetObjectParameterivARB &&
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218 glGetUniformLocationARB &&
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219 glLinkProgramARB &&
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220 glShaderSourceARB &&
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221 glUniform1iARB &&
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222 glUseProgramObjectARB) {
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223 shaders_supported = SDL_TRUE;
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224 }
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225 }
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226
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227 if (!shaders_supported) {
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228 return SDL_FALSE;
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229 }
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230
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231 /* Compile all the shaders */
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232 for (i = 0; i < NUM_SHADERS; ++i) {
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diff changeset
233 if (!CompileShaderProgram(&shaders[i])) {
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234 fprintf(stderr, "Unable to compile shader!\n");
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235 return SDL_FALSE;
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236 }
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diff changeset
237 }
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238
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239 /* We're done! */
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240 return SDL_TRUE;
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241 }
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242
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
243 static void QuitShaders()
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diff changeset
244 {
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245 int i;
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diff changeset
246
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
247 for (i = 0; i < NUM_SHADERS; ++i) {
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248 DestroyShaderProgram(&shaders[i]);
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249 }
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diff changeset
250 }
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251
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
252 /* Quick utility function for texture creation */
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diff changeset
253 static int
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
254 power_of_two(int input)
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diff changeset
255 {
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diff changeset
256 int value = 1;
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257
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
258 while (value < input) {
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diff changeset
259 value <<= 1;
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diff changeset
260 }
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diff changeset
261 return value;
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diff changeset
262 }
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diff changeset
263
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
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diff changeset
264 GLuint
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diff changeset
265 SDL_GL_LoadTexture(SDL_Surface * surface, GLfloat * texcoord)
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diff changeset
266 {
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diff changeset
267 GLuint texture;
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diff changeset
268 int w, h;
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
269 SDL_Surface *image;
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diff changeset
270 SDL_Rect area;
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diff changeset
271 Uint32 saved_flags;
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272 Uint8 saved_alpha;
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diff changeset
273
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
274 /* Use the surface width and height expanded to powers of 2 */
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diff changeset
275 w = power_of_two(surface->w);
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diff changeset
276 h = power_of_two(surface->h);
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diff changeset
277 texcoord[0] = 0.0f; /* Min X */
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diff changeset
278 texcoord[1] = 0.0f; /* Min Y */
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diff changeset
279 texcoord[2] = (GLfloat) surface->w / w; /* Max X */
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diff changeset
280 texcoord[3] = (GLfloat) surface->h / h; /* Max Y */
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281
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diff changeset
282 image = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32,
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diff changeset
283 #if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */
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284 0x000000FF,
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diff changeset
285 0x0000FF00, 0x00FF0000, 0xFF000000
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diff changeset
286 #else
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diff changeset
287 0xFF000000,
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diff changeset
288 0x00FF0000, 0x0000FF00, 0x000000FF
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diff changeset
289 #endif
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parents:
diff changeset
290 );
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diff changeset
291 if (image == NULL) {
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
292 return 0;
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
293 }
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294
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
295 /* Save the alpha blending attributes */
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diff changeset
296 saved_flags = surface->flags & (SDL_SRCALPHA | SDL_RLEACCELOK);
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diff changeset
297 SDL_GetSurfaceAlphaMod(surface, &saved_alpha);
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diff changeset
298 if ((saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA) {
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diff changeset
299 SDL_SetAlpha(surface, 0, 0);
74bc160186a8 Added a simple GLSL example using SDL
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diff changeset
300 }
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diff changeset
301
74bc160186a8 Added a simple GLSL example using SDL
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parents:
diff changeset
302 /* Copy the surface into the GL texture image */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
303 area.x = 0;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
304 area.y = 0;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
305 area.w = surface->w;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
306 area.h = surface->h;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
307 SDL_BlitSurface(surface, &area, image, &area);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
308
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
309 /* Restore the alpha blending attributes */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
310 if ((saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
311 SDL_SetAlpha(surface, saved_flags, saved_alpha);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
312 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
313
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
314 /* Create an OpenGL texture for the image */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
315 glGenTextures(1, &texture);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
316 glBindTexture(GL_TEXTURE_2D, texture);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
317 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
318 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
319 glTexImage2D(GL_TEXTURE_2D,
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
320 0,
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
321 GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
322 SDL_FreeSurface(image); /* No longer needed */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
323
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
324 return texture;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
325 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
326
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
327 /* A general OpenGL initialization function. Sets all of the initial parameters. */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
328 void InitGL(int Width, int Height) // We call this right after our OpenGL window is created.
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
329 {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
330 GLdouble aspect;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
331
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
332 glViewport(0, 0, Width, Height);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
333 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // This Will Clear The Background Color To Black
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
334 glClearDepth(1.0); // Enables Clearing Of The Depth Buffer
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
335 glDepthFunc(GL_LESS); // The Type Of Depth Test To Do
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
336 glEnable(GL_DEPTH_TEST); // Enables Depth Testing
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
337 glShadeModel(GL_SMOOTH); // Enables Smooth Color Shading
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
338
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
339 glMatrixMode(GL_PROJECTION);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
340 glLoadIdentity(); // Reset The Projection Matrix
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
341
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
342 aspect = (GLdouble)Width / Height;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
343 glOrtho(-3.0, 3.0, -3.0 / aspect, 3.0 / aspect, 0.0, 1.0);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
344
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
345 glMatrixMode(GL_MODELVIEW);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
346 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
347
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
348 /* The main drawing function. */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
349 void DrawGLScene(GLuint texture, GLfloat * texcoord)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
350 {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
351 /* Texture coordinate lookup, to make it simple */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
352 enum {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
353 MINX,
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
354 MINY,
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
355 MAXX,
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
356 MAXY
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
357 };
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
358
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
359 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
360 glLoadIdentity(); // Reset The View
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
361
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
362 glTranslatef(-1.5f,0.0f,0.0f); // Move Left 1.5 Units
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
363
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
364 // draw a triangle (in smooth coloring mode)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
365 glBegin(GL_POLYGON); // start drawing a polygon
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
366 glColor3f(1.0f,0.0f,0.0f); // Set The Color To Red
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
367 glVertex3f( 0.0f, 1.0f, 0.0f); // Top
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
368 glColor3f(0.0f,1.0f,0.0f); // Set The Color To Green
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
369 glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
370 glColor3f(0.0f,0.0f,1.0f); // Set The Color To Blue
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
371 glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
372 glEnd(); // we're done with the polygon (smooth color interpolation)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
373
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
374 glTranslatef(3.0f,0.0f,0.0f); // Move Right 3 Units
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
375
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
376 // Enable blending
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
377 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
378 glEnable(GL_BLEND);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
379 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
380
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
381 // draw a textured square (quadrilateral)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
382 glEnable(GL_TEXTURE_2D);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
383 glBindTexture(GL_TEXTURE_2D, texture);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
384 glColor3f(1.0f,1.0f,1.0f);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
385 if (shaders_supported) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
386 glUseProgramObjectARB(shaders[current_shader].program);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
387 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
388
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
389 glBegin(GL_QUADS); // start drawing a polygon (4 sided)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
390 glTexCoord2f(texcoord[MINX], texcoord[MINY]);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
391 glVertex3f(-1.0f, 1.0f, 0.0f); // Top Left
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
392 glTexCoord2f(texcoord[MAXX], texcoord[MINY]);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
393 glVertex3f( 1.0f, 1.0f, 0.0f); // Top Right
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
394 glTexCoord2f(texcoord[MAXX], texcoord[MAXY]);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
395 glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
396 glTexCoord2f(texcoord[MINX], texcoord[MAXY]);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
397 glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
398 glEnd(); // done with the polygon
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
399
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
400 if (shaders_supported) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
401 glUseProgramObjectARB(0);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
402 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
403 glDisable(GL_TEXTURE_2D);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
404
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
405 // swap buffers to display, since we're double buffered.
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
406 SDL_GL_SwapBuffers();
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
407 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
408
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
409 int main(int argc, char **argv)
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
410 {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
411 int done;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
412 SDL_Surface *surface;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
413 GLuint texture;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
414 GLfloat texcoords[4];
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
415
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
416 /* Initialize SDL for video output */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
417 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
418 fprintf(stderr, "Unable to initialize SDL: %s\n", SDL_GetError());
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
419 exit(1);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
420 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
421
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
422 /* Create a 640x480 OpenGL screen */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
423 if ( SDL_SetVideoMode(640, 480, 0, SDL_OPENGL) == NULL ) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
424 fprintf(stderr, "Unable to create OpenGL screen: %s\n", SDL_GetError());
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
425 SDL_Quit();
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
426 exit(2);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
427 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
428
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
429 /* Set the title bar in environments that support it */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
430 SDL_WM_SetCaption("Shader Demo", NULL);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
431
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
432 surface = SDL_LoadBMP("icon.bmp");
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
433 if ( ! surface ) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
434 fprintf(stderr, "Unable to load icon.bmp: %s\n", SDL_GetError());
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
435 SDL_Quit();
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
436 exit(3);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
437 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
438 texture = SDL_GL_LoadTexture(surface, texcoords);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
439 SDL_FreeSurface(surface);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
440
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
441 /* Loop, drawing and checking events */
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
442 InitGL(640, 480);
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
443 if (InitShaders()) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
444 printf("Shaders supported, press SPACE to cycle them.\n");
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
445 } else {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
446 printf("Shaders not supported!\n");
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
447 }
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
448 done = 0;
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
449 while ( ! done ) {
74bc160186a8 Added a simple GLSL example using SDL
Sam Lantinga <slouken@libsdl.org>
parents:
diff changeset
450 DrawGLScene(texture, texcoords);
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451
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452 /* This could go in a separate function */
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453 { SDL_Event event;
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454 while ( SDL_PollEvent(&event) ) {
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455 if ( event.type == SDL_QUIT ) {
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456 done = 1;
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457 }
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458 if ( event.type == SDL_KEYDOWN ) {
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459 if ( event.key.keysym.sym == SDLK_SPACE ) {
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460 current_shader = (current_shader + 1) % NUM_SHADERS;
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461 }
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462 if ( event.key.keysym.sym == SDLK_ESCAPE ) {
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463 done = 1;
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464 }
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465 }
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466 }
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467 }
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468 }
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469 QuitShaders();
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470 SDL_Quit();
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471 return 1;
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472 }
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473
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474 #else /* HAVE_OPENGL */
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475
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476 int
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477 main(int argc, char *argv[])
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478 {
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479 printf("No OpenGL support on this system\n");
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480 return 1;
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481 }
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482
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483 #endif /* HAVE_OPENGL */