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comparison Xcode-iPhoneOS/Demos/src/accelerometer.c @ 3690:e431b888ac6c

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Fixed compilation on iPhone
author Sam Lantinga <slouken@libsdl.org>
date Thu, 21 Jan 2010 16:12:24 +0000
parents 64ce267332c6
children 78db79f5a4e2
comparison
equal deleted inserted replaced
3689:af25b5586af7 3690:e431b888ac6c
23 static struct 23 static struct
24 { 24 {
25 float x, y; /* position of ship */ 25 float x, y; /* position of ship */
26 float vx, vy; /* velocity of ship (in pixels per millesecond) */ 26 float vx, vy; /* velocity of ship (in pixels per millesecond) */
27 SDL_Rect rect; /* (drawn) position and size of ship */ 27 SDL_Rect rect; /* (drawn) position and size of ship */
28 } ship; 28 } shipData;
29 29
30 static SDL_Texture *ship = 0; /* texture for spaceship */ 30 static SDL_Texture *ship = 0; /* texture for spaceship */
31 static SDL_Texture *space = 0; /* texture for space (background */ 31 static SDL_Texture *space = 0; /* texture for space (background */
32 32
33 void 33 void
39 float ax = SDL_JoystickGetAxis(accelerometer, 0); 39 float ax = SDL_JoystickGetAxis(accelerometer, 0);
40 float ay = -SDL_JoystickGetAxis(accelerometer, 1); 40 float ay = -SDL_JoystickGetAxis(accelerometer, 1);
41 41
42 /* ship screen constraints */ 42 /* ship screen constraints */
43 Uint32 minx = 0.0f; 43 Uint32 minx = 0.0f;
44 Uint32 maxx = SCREEN_WIDTH - ship.rect.w; 44 Uint32 maxx = SCREEN_WIDTH - shipData.rect.w;
45 Uint32 miny = 0.0f; 45 Uint32 miny = 0.0f;
46 Uint32 maxy = SCREEN_HEIGHT - ship.rect.h; 46 Uint32 maxy = SCREEN_HEIGHT - shipData.rect.h;
47 47
48 #define SINT16_MAX ((float)(0x7FFF)) 48 #define SINT16_MAX ((float)(0x7FFF))
49 49
50 /* update velocity from accelerometer 50 /* update velocity from accelerometer
51 the factor SDL_IPHONE_MAX_G_FORCE / SINT16_MAX converts between 51 the factor SDL_IPHONE_MAX_G_FORCE / SINT16_MAX converts between
52 SDL's units reported from the joytick, and units of g-force, as reported by the accelerometer 52 SDL's units reported from the joytick, and units of g-force, as reported by the accelerometer
53 */ 53 */
54 ship.vx += 54 shipData.vx +=
55 ax * SDL_IPHONE_MAX_GFORCE / SINT16_MAX * GRAVITY_CONSTANT * 55 ax * SDL_IPHONE_MAX_GFORCE / SINT16_MAX * GRAVITY_CONSTANT *
56 MILLESECONDS_PER_FRAME; 56 MILLESECONDS_PER_FRAME;
57 ship.vy += 57 shipData.vy +=
58 ay * SDL_IPHONE_MAX_GFORCE / SINT16_MAX * GRAVITY_CONSTANT * 58 ay * SDL_IPHONE_MAX_GFORCE / SINT16_MAX * GRAVITY_CONSTANT *
59 MILLESECONDS_PER_FRAME; 59 MILLESECONDS_PER_FRAME;
60 60
61 float speed = sqrt(ship.vx * ship.vx + ship.vy * ship.vy); 61 float speed = sqrt(shipData.vx * shipData.vx + shipData.vy * shipData.vy);
62 62
63 if (speed > 0) { 63 if (speed > 0) {
64 /* compensate for friction */ 64 /* compensate for friction */
65 float dirx = ship.vx / speed; /* normalized x velocity */ 65 float dirx = shipData.vx / speed; /* normalized x velocity */
66 float diry = ship.vy / speed; /* normalized y velocity */ 66 float diry = shipData.vy / speed; /* normalized y velocity */
67 67
68 /* update velocity due to friction */ 68 /* update velocity due to friction */
69 if (speed - FRICTION * MILLESECONDS_PER_FRAME > 0) { 69 if (speed - FRICTION * MILLESECONDS_PER_FRAME > 0) {
70 /* apply friction */ 70 /* apply friction */
71 ship.vx -= dirx * FRICTION * MILLESECONDS_PER_FRAME; 71 shipData.vx -= dirx * FRICTION * MILLESECONDS_PER_FRAME;
72 ship.vy -= diry * FRICTION * MILLESECONDS_PER_FRAME; 72 shipData.vy -= diry * FRICTION * MILLESECONDS_PER_FRAME;
73 } else { 73 } else {
74 /* applying friction would MORE than stop the ship, so just stop the ship */ 74 /* applying friction would MORE than stop the ship, so just stop the ship */
75 ship.vx = 0.0f; 75 shipData.vx = 0.0f;
76 ship.vy = 0.0f; 76 shipData.vy = 0.0f;
77 } 77 }
78 } 78 }
79 79
80 /* update ship location */ 80 /* update ship location */
81 ship.x += ship.vx * MILLESECONDS_PER_FRAME; 81 shipData.x += shipData.vx * MILLESECONDS_PER_FRAME;
82 ship.y += ship.vy * MILLESECONDS_PER_FRAME; 82 shipData.y += shipData.vy * MILLESECONDS_PER_FRAME;
83 83
84 if (ship.x > maxx) { 84 if (shipData.x > maxx) {
85 ship.x = maxx; 85 shipData.x = maxx;
86 ship.vx = -ship.vx * DAMPING; 86 shipData.vx = -shipData.vx * DAMPING;
87 } else if (ship.x < minx) { 87 } else if (shipData.x < minx) {
88 ship.x = minx; 88 shipData.x = minx;
89 ship.vx = -ship.vx * DAMPING; 89 shipData.vx = -shipData.vx * DAMPING;
90 } 90 }
91 if (ship.y > maxy) { 91 if (shipData.y > maxy) {
92 ship.y = maxy; 92 shipData.y = maxy;
93 ship.vy = -ship.vy * DAMPING; 93 shipData.vy = -shipData.vy * DAMPING;
94 } else if (ship.y < miny) { 94 } else if (shipData.y < miny) {
95 ship.y = miny; 95 shipData.y = miny;
96 ship.vy = -ship.vy * DAMPING; 96 shipData.vy = -shipData.vy * DAMPING;
97 } 97 }
98 98
99 /* draw the background */ 99 /* draw the background */
100 SDL_RenderCopy(space, NULL, NULL); 100 SDL_RenderCopy(space, NULL, NULL);
101 101
102 /* draw the ship */ 102 /* draw the ship */
103 ship.rect.x = ship.x; 103 shipData.rect.x = shipData.x;
104 ship.rect.y = ship.y; 104 shipData.rect.y = shipData.y;
105 105
106 SDL_RenderCopy(ship, NULL, &ship.rect); 106 SDL_RenderCopy(ship, NULL, &shipData.rect);
107 107
108 /* update screen */ 108 /* update screen */
109 SDL_RenderPresent(); 109 SDL_RenderPresent();
110 110
111 } 111 }
146 fatalError("could not create ship texture"); 146 fatalError("could not create ship texture");
147 } 147 }
148 SDL_SetTextureBlendMode(ship, SDL_BLENDMODE_BLEND); 148 SDL_SetTextureBlendMode(ship, SDL_BLENDMODE_BLEND);
149 149
150 /* set the width and height of the ship from the surface dimensions */ 150 /* set the width and height of the ship from the surface dimensions */
151 ship.rect.w = bmp_surface->w; 151 shipData.rect.w = bmp_surface->w;
152 ship.rect.h = bmp_surface->h; 152 shipData.rect.h = bmp_surface->h;
153 153
154 SDL_FreeSurface(bmp_surface_rgba); 154 SDL_FreeSurface(bmp_surface_rgba);
155 SDL_FreeSurface(bmp_surface); 155 SDL_FreeSurface(bmp_surface);
156 156
157 /* load the space background */ 157 /* load the space background */
209 209
210 /* load graphics */ 210 /* load graphics */
211 initializeTextures(); 211 initializeTextures();
212 212
213 /* setup ship */ 213 /* setup ship */
214 ship.x = (SCREEN_WIDTH - ship.rect.w) / 2; 214 shipData.x = (SCREEN_WIDTH - shipData.rect.w) / 2;
215 ship.y = (SCREEN_HEIGHT - ship.rect.h) / 2; 215 shipData.y = (SCREEN_HEIGHT - shipData.rect.h) / 2;
216 ship.vx = 0.0f; 216 shipData.vx = 0.0f;
217 ship.vy = 0.0f; 217 shipData.vy = 0.0f;
218 218
219 done = 0; 219 done = 0;
220 /* enter main loop */ 220 /* enter main loop */
221 while (!done) { 221 while (!done) {
222 startFrame = SDL_GetTicks(); 222 startFrame = SDL_GetTicks();