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comparison src/video/SDL_renderer_gl.c @ 3475:3bd01435287f

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Added comment for pixel-perfect line workaround.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Nov 2009 07:26:52 +0000
parents 1edb86163d62
children 6f887204fa7a
comparison
equal deleted inserted replaced
3474:1edb86163d62 3475:3bd01435287f
1155 data->glVertex2f(0.5f + x2, 0.5f + y2); 1155 data->glVertex2f(0.5f + x2, 0.5f + y2);
1156 data->glEnd(); 1156 data->glEnd();
1157 1157
1158 /* The line is half open, so we need one more point to complete the line. 1158 /* The line is half open, so we need one more point to complete the line.
1159 * http://www.opengl.org/documentation/specs/version1.1/glspec1.1/node47.html 1159 * http://www.opengl.org/documentation/specs/version1.1/glspec1.1/node47.html
1160 * If we have to, we can use vertical line and horizontal line textures
1161 * for vertical and horizontal lines, and then create custom textures
1162 * for diagonal lines and software render those. It's terrible, but at
1163 * least it would be pixel perfect.
1160 */ 1164 */
1161 data->glBegin(GL_POINTS); 1165 data->glBegin(GL_POINTS);
1162 #ifdef __APPLE__ 1166 #ifdef __APPLE__
1163 /* Mac OS X seems to always leave the second point open */ 1167 /* Mac OS X seems to always leave the second point open */
1164 data->glVertex2f(0.5f + x2, 0.5f + y2); 1168 data->glVertex2f(0.5f + x2, 0.5f + y2);
1165 #else 1169 #else
1166 /* Linux seems to use the right-most or bottom-most point open */ 1170 /* Linux seems to leave the right-most or bottom-most point open */
1167 if (x1 > x2) { 1171 if (x1 > x2) {
1168 data->glVertex2f(0.5f + x1, 0.5f + y1); 1172 data->glVertex2f(0.5f + x1, 0.5f + y1);
1169 } else if (x2 > x1) { 1173 } else if (x2 > x1) {
1170 data->glVertex2f(0.5f + x2, 0.5f + y2); 1174 data->glVertex2f(0.5f + x2, 0.5f + y2);
1171 } else if (y1 > y2) { 1175 } else if (y1 > y2) {