当我学习OpenGL ES时，我稍微修改了iPhone SDK的GLSprite示例，结果发现它非常慢。即使在模拟器上（硬件最差的情况下），所以我一定做错了什么，因为它只有400个纹理三角形。
const GLfloat spriteVertices[] = {
0.0f, 0.0f,
100.0f, 0.0f,
0.0f, 100.0f,
100.0f, 100.0f
};
const GLshort spriteTexcoords[] = {
0,0,
1,0,
0,1,
1,1
};
- (void)setupView {
glViewport(0, 0, backingWidth, backingHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(0.0f, backingWidth, backingHeight,0.0f, -10.0f, 10.0f);
glMatrixMode(GL_MODELVIEW);
glClearColor(0.3f, 0.0f, 0.0f, 1.0f);
glVertexPointer(2, GL_FLOAT, 0, spriteVertices);
glEnableClientState(GL_VERTEX_ARRAY);
glTexCoordPointer(2, GL_SHORT, 0, spriteTexcoords);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
// sprite data is preloaded. 512x512 rgba8888
glGenTextures(1, &spriteTexture);
glBindTexture(GL_TEXTURE_2D, spriteTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);
free(spriteData);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glEnable(GL_TEXTURE_2D);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
}
- (void)drawView {
..
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glTranslatef(tx-100, ty-100,10);
for (int i=0; i<200; i++) {
glTranslatef(1, 1, 0);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
..
}
每次触摸屏幕或手指在屏幕上移动时都会调用drawView，并将tx，ty设置为触摸发生的x，y坐标。
我也尝试使用GLBuffer，当翻译是预生成的且只有一个DrawArray时，但是性能相同（约4帧/秒）。
===编辑===
Meanwhile I ve modified this so that much smaller quads are used (sized: 34x20) and much less overlapping is done. There are ~400 quads->800 triangles spread on the whole screen. Texture size is 512x512 atlas and RGBA_8888 while the texture coordinates are in float. The code is very ugly in terms of API efficiency: there are two MatrixMode change along with two loads and two translation then a drawarrays for a triangle strip (quad). Now this produces ~45 FPS.