在我找到真正的文本数据在 alpha 通道中之前,我花了太多时间看着黑屏。
GLuint shader_program_text;
void drawText()
{
text_font = TTF_OpenFont("bpl_binary/waltographUI.ttf", 50);
SDL_Color color = {255, 0, 0, 0};
SDL_Surface* sdl_surface = TTF_RenderText_Blended(text_font, "hello world", color);
GLuint texture_id;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, sdl_surface->w, sdl_surface->h, 0, GL_BGRA, GL_UNSIGNED_BYTE, sdl_surface->pixels);
glBindTexture(GL_TEXTURE_2D, 0);
SDL_FreeSurface(sdl_surface);
TTF_CloseFont(text_font);
glUseProgram(shader_program_text);
glEnable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture_id);
glBegin(GL_TRIANGLE_STRIP);
glVertexAttrib2f(1, 0, 1); glVertexAttrib2f(0, -1, -1);
glVertexAttrib2f(1, 1, 1); glVertexAttrib2f(0, +1, -1);
glVertexAttrib2f(1, 0, 0); glVertexAttrib2f(0, -1, +1);
glVertexAttrib2f(1, 1, 0); glVertexAttrib2f(0, +1, +1);
glEnd();
glDisable(GL_TEXTURE_2D);
glUseProgram(0);
}