From e973b687cdcb5b6aee40c18ac0ae99f9323e9f1b Mon Sep 17 00:00:00 2001 From: "Ryan C. Gordon" Date: Mon, 23 Sep 2024 01:21:24 -0400 Subject: [PATCH] examples: Added renderer/11-color-mods --- examples/CMakeLists.txt | 1 + examples/renderer/11-color-mods/README.txt | 3 + examples/renderer/11-color-mods/color-mods.c | 132 +++++++++++++++++++ 3 files changed, 136 insertions(+) create mode 100644 examples/renderer/11-color-mods/README.txt create mode 100644 examples/renderer/11-color-mods/color-mods.c diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index e35e49da13..92b02afb19 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -130,6 +130,7 @@ add_sdl_example_executable(renderer-streaming-textures SOURCES renderer/07-strea add_sdl_example_executable(renderer-rotating-textures SOURCES renderer/08-rotating-textures/rotating-textures.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.bmp) add_sdl_example_executable(renderer-scaling-textures SOURCES renderer/09-scaling-textures/scaling-textures.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.bmp) add_sdl_example_executable(renderer-geometry SOURCES renderer/10-geometry/geometry.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.bmp) +add_sdl_example_executable(renderer-color-mods SOURCES renderer/11-color-mods/color-mods.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.bmp) add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playback/simple-playback.c) add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simple-playback-callback/simple-playback-callback.c) add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav) diff --git a/examples/renderer/11-color-mods/README.txt b/examples/renderer/11-color-mods/README.txt new file mode 100644 index 0000000000..66f233b613 --- /dev/null +++ b/examples/renderer/11-color-mods/README.txt @@ -0,0 +1,3 @@ +This example creates an SDL window and renderer, loads a texture from a +.bmp file, and then draws it a few times each frame, adjusting the colors. + diff --git a/examples/renderer/11-color-mods/color-mods.c b/examples/renderer/11-color-mods/color-mods.c new file mode 100644 index 0000000000..21ae66a024 --- /dev/null +++ b/examples/renderer/11-color-mods/color-mods.c @@ -0,0 +1,132 @@ +/* + * This example creates an SDL window and renderer, and then draws some + * textures to it every frame, adjusting their color. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ +#include +#include + +/* We will use this renderer to draw into this window every frame. */ +static SDL_Window *window = NULL; +static SDL_Renderer *renderer = NULL; +static SDL_Texture *texture = NULL; +static int texture_width = 0; +static int texture_height = 0; + +#define WINDOW_WIDTH 640 +#define WINDOW_HEIGHT 480 + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + SDL_Surface *surface = NULL; + char *bmp_path = NULL; + + if (!SDL_Init(SDL_INIT_VIDEO)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't initialize SDL!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/renderer/color-mods", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + /* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D + engines refer to these as "sprites." We'll do a static texture (upload once, draw many + times) with data from a bitmap file. */ + + /* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access. + Load a .bmp into a surface, move it to a texture from there. */ + SDL_asprintf(&bmp_path, "%ssample.bmp", SDL_GetBasePath()); /* allocate a string of the full file path */ + surface = SDL_LoadBMP(bmp_path); + if (!surface) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't load bitmap!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + SDL_free(bmp_path); /* done with this, the file is loaded. */ + + texture_width = surface->w; + texture_height = surface->h; + + texture = SDL_CreateTextureFromSurface(renderer, surface); + if (!texture) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create static texture!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + SDL_DestroySurface(surface); /* done with this, the texture has a copy of the pixels now. */ + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ +SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) +{ + if (event->type == SDL_EVENT_QUIT) { + return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ + } + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once per frame, and is the heart of the program. */ +SDL_AppResult SDL_AppIterate(void *appstate) +{ + SDL_FRect dst_rect; + const double now = ((double)SDL_GetTicks()) / 1000.0; /* convert from milliseconds to seconds. */ + /* choose the modulation values for the center texture. The sine wave trick makes it fade between colors smoothly. */ + const float red = (float) (0.5 + 0.5 * SDL_sin(now)); + const float green = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 2 / 3)); + const float blue = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 4 / 3)); + + /* as you can see from this, rendering draws over whatever was drawn before it. */ + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); /* black, full alpha */ + SDL_RenderClear(renderer); /* start with a blank canvas. */ + + /* Just draw the static texture a few times. You can think of it like a + stamp, there isn't a limit to the number of times you can draw with it. */ + + /* Color modulation multiplies each pixel's red, green, and blue intensities by the mod values, + so multiplying by 1.0f will leave a color intensity alone, 0.0f will shut off that color + completely, etc. */ + + /* top left; let's make this one blue! */ + dst_rect.x = 0.0f; + dst_rect.y = 0.0f; + dst_rect.w = (float) texture_width; + dst_rect.h = (float) texture_height; + SDL_SetTextureColorModFloat(texture, 0.0f, 0.0f, 1.0f); /* kill all red and green. */ + SDL_RenderTexture(renderer, texture, NULL, &dst_rect); + + /* center this one, and have it cycle through red/green/blue modulations. */ + dst_rect.x = ((float) (WINDOW_WIDTH - texture_width)) / 2.0f; + dst_rect.y = ((float) (WINDOW_HEIGHT - texture_height)) / 2.0f; + dst_rect.w = (float) texture_width; + dst_rect.h = (float) texture_height; + SDL_SetTextureColorModFloat(texture, red, green, blue); + SDL_RenderTexture(renderer, texture, NULL, &dst_rect); + + /* bottom right; let's make this one red! */ + dst_rect.x = (float) (WINDOW_WIDTH - texture_width); + dst_rect.y = (float) (WINDOW_HEIGHT - texture_height); + dst_rect.w = (float) texture_width; + dst_rect.h = (float) texture_height; + SDL_SetTextureColorModFloat(texture, 1.0f, 0.0f, 0.0f); /* kill all green and blue. */ + SDL_RenderTexture(renderer, texture, NULL, &dst_rect); + + SDL_RenderPresent(renderer); /* put it all on the screen! */ + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate) +{ + SDL_DestroyTexture(texture); + /* SDL will clean up the window/renderer for us. */ +} +