OpenGL文本方法
使用OpenGL可以更容易地找到高效的实现,因为它比SDL更广泛地使用,详见:如何仅使用OpenGL方法绘制文本?
目前,我建议使用freetype-gl:https://github.com/rougier/freetype-gl,该库支持开箱即用的纹理图集https://en.wikipedia.org/wiki/Texture_atlas。
SDL对OpenGL支持良好,如果你已经在程序中使用了SDL纹理,甚至可以在单个程序中同时使用GL和SDL纹理,例如:
#include <SDL2/SDL.h>
#define GLEW_STATIC
#include <GL/glew.h>
int main(void) {
SDL_GLContext gl_context;
SDL_Event event;
SDL_Renderer *renderer = NULL;
SDL_Texture *texture = NULL;
SDL_Window *window = NULL;
Uint8 *base;
const unsigned int
WINDOW_WIDTH = 500,
WINDOW_HEIGHT = WINDOW_WIDTH
;
int pitch;
unsigned int x, y;
void *pixels = NULL;
SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO);
window = SDL_CreateWindow(
__FILE__, 0, 0,
WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_OPENGL
);
renderer = SDL_CreateRenderer(window, 0, 0);
gl_context = SDL_GL_CreateContext(window);
glClearColor(1.0, 0.0, 1.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
SDL_TEXTUREACCESS_STREAMING, WINDOW_WIDTH, WINDOW_HEIGHT);
SDL_LockTexture(texture, NULL, &pixels, &pitch);
for (x = 0; x < WINDOW_WIDTH; x++) {
for (y = 0; y < WINDOW_HEIGHT; y++) {
base = ((Uint8 *)pixels) + (4 * (x * WINDOW_WIDTH + y));
base[0] = 0;
base[1] = 0;
base[2] = 255;
base[3] = 255;
}
}
SDL_UnlockTexture(texture);
SDL_Rect rect;
rect.x = 0;
rect.y = 0;
rect.w = WINDOW_WIDTH / 2;
rect.h = WINDOW_HEIGHT / 2;
SDL_RenderCopy(renderer, texture, NULL, &rect);
SDL_GL_SwapWindow(window);
while (1) {
if (SDL_PollEvent(&event) && event.type == SDL_QUIT)
break;
}
SDL_GL_DeleteContext(gl_context);
SDL_DestroyTexture(texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return EXIT_SUCCESS;
}
编译并运行:
gcc -std=c99 main.c -lSDL2 -lGL
./a.out
已在Ubuntu 17.10中测试。
GitHub源代码:https://github.com/cirosantilli/cpp-cheat/blob/d36527fe4977bb9ef4b885b1ec92bd0cd3444a98/sdl/texture_and_opengl.c