Atlas - affine-textures.c
Home / ext / SDL / examples / renderer / 19-affine-textures Lines: 1 | Size: 5589 bytes [Download] [Show on GitHub] [Search similar files] [Raw] [Raw (proxy)][FILE BEGIN]1/* affine-textures.c ... */ 2 3/* 4* This example creates an SDL window and renderer, and then draws a cube 5* using affine-transformed textures every frame. 6* 7* This code is public domain. Feel free to use it for any purpose! 8*/ 9 10#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ 11#include <SDL3/SDL.h> 12#include <SDL3/SDL_main.h> 13 14/* We will use this renderer to draw into this window every frame. */ 15static SDL_Window *window = NULL; 16static SDL_Renderer *renderer = NULL; 17static SDL_Texture *texture = NULL; 18static int texture_width = 0; 19static int texture_height = 0; 20 21#define WINDOW_WIDTH 640 22#define WINDOW_HEIGHT 480 23 24/* This function runs once at startup. */ 25SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) 26{ 27 SDL_Surface *surface = NULL; 28 char *png_path = NULL; 29 30 SDL_SetAppMetadata("Example Renderer Affine Textures", "1.0", "com.example.renderer-affine-textures"); 31 32 if (!SDL_Init(SDL_INIT_VIDEO)) { 33 SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); 34 return SDL_APP_FAILURE; 35 } 36 37 if (!SDL_CreateWindowAndRenderer("examples/renderer/affine-textures", WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_RESIZABLE, &window, &renderer)) { 38 SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); 39 return SDL_APP_FAILURE; 40 } 41 SDL_SetRenderLogicalPresentation(renderer, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_LOGICAL_PRESENTATION_LETTERBOX); 42 43 /* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D 44 engines refer to these as "sprites." We'll do a static texture (upload once, draw many 45 times) with data from a bitmap file. */ 46 47 /* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access. 48 Load a .png into a surface, move it to a texture from there. */ 49 SDL_asprintf(&png_path, "%ssample.png", SDL_GetBasePath()); /* allocate a string of the full file path */ 50 surface = SDL_LoadPNG(png_path); 51 if (!surface) { 52 SDL_Log("Couldn't load bitmap: %s", SDL_GetError()); 53 return SDL_APP_FAILURE; 54 } 55 56 SDL_free(png_path); /* done with this, the file is loaded. */ 57 58 texture_width = surface->w; 59 texture_height = surface->h; 60 61 texture = SDL_CreateTextureFromSurface(renderer, surface); 62 if (!texture) { 63 SDL_Log("Couldn't create static texture: %s", SDL_GetError()); 64 return SDL_APP_FAILURE; 65 } 66 67 SDL_DestroySurface(surface); /* done with this, the texture has a copy of the pixels now. */ 68 69 return SDL_APP_CONTINUE; /* carry on with the program! */ 70} 71 72/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ 73SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) 74{ 75 if (event->type == SDL_EVENT_QUIT) { 76 return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ 77 } 78 return SDL_APP_CONTINUE; /* carry on with the program! */ 79} 80 81/* This function runs once per frame, and is the heart of the program. */ 82SDL_AppResult SDL_AppIterate(void *appstate) 83{ 84 const float x0 = 0.5f * WINDOW_WIDTH; 85 const float y0 = 0.5f * WINDOW_HEIGHT; 86 const float px = SDL_min(WINDOW_WIDTH, WINDOW_HEIGHT) / SDL_sqrtf(3.0f); 87 88 const Uint64 now = SDL_GetTicks(); 89 const float rad = (((float) ((int) (now % 2000))) / 2000.0f) * SDL_PI_F * 2; 90 const float cos = SDL_cosf(rad); 91 const float sin = SDL_sinf(rad); 92 const float k[3] = { 3.0f / SDL_sqrtf(50.0f), 4.0f / SDL_sqrtf(50.0f), 5.0f / SDL_sqrtf(50.0f)}; 93 float mat[9] = { 94 cos + (1.0f-cos)*k[0]*k[0], -sin*k[2] + (1.0f-cos)*k[0]*k[1], sin*k[1] + (1.0f-cos)*k[0]*k[2], 95 sin*k[2] + (1.0f-cos)*k[0]*k[1], cos + (1.0f-cos)*k[1]*k[1], -sin*k[0] + (1.0f-cos)*k[1]*k[2], 96 -sin*k[1] + (1.0f-cos)*k[0]*k[2], sin*k[0] + (1.0f-cos)*k[1]*k[2], cos + (1.0f-cos)*k[2]*k[2], 97 }; 98 99 float corners[16]; 100 int i; 101 102 for (i = 0; i < 8; i++) { 103 const float x = (i & 1) ? -0.5f : 0.5f; 104 const float y = (i & 2) ? -0.5f : 0.5f; 105 const float z = (i & 4) ? -0.5f : 0.5f; 106 corners[0 + 2*i] = mat[0]*x + mat[1]*y + mat[2]*z; 107 corners[1 + 2*i] = mat[3]*x + mat[4]*y + mat[5]*z; 108 } 109 110 SDL_SetRenderDrawColor(renderer, 0x42, 0x87, 0xf5, SDL_ALPHA_OPAQUE); // light blue background. 111 SDL_RenderClear(renderer); 112 113 for (i = 1; i < 7; i++) { 114 const int dir = 3 & ((i & 4) ? ~i : i); 115 const int odd = (i & 1) ^ ((i & 2) >> 1) ^ ((i & 4) >> 2); 116 if (0 < (odd ? 1.0f : -1.0f) * mat[5 + dir]) continue; 117 int origin_index = (1 << ((dir - 1) % 3)); 118 int right_index = (1 << ((dir + odd) % 3)) | origin_index; 119 int down_index = (1 << ((dir + (odd^1)) % 3)) | origin_index; 120 if (!odd) { 121 origin_index ^= 7; 122 right_index ^= 7; 123 down_index ^= 7; 124 } 125 SDL_FPoint origin, right, down; 126 origin.x = x0 + px*corners[0 + 2*origin_index]; 127 origin.y = y0 + px*corners[1 + 2*origin_index]; 128 right.x = x0 + px*corners[0 + 2*right_index]; 129 right.y = y0 + px*corners[1 + 2*right_index]; 130 down.x = x0 + px*corners[0 + 2*down_index]; 131 down.y = y0 + px*corners[1 + 2*down_index]; 132 SDL_RenderTextureAffine(renderer, texture, NULL, &origin, &right, &down); 133 } 134 135 SDL_RenderPresent(renderer); 136 137 return SDL_APP_CONTINUE; 138} 139 140/* This function runs once at shutdown. */ 141void SDL_AppQuit(void *appstate, SDL_AppResult result) 142{ 143 SDL_DestroyTexture(texture); 144 /* SDL will clean up the window/renderer for us. */ 145} 146 147[FILE END](C) 2025 0x4248 (C) 2025 4248 Media and 4248 Systems, All part of 0x4248 See LICENCE files for more information. 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