iphone - Implementing a Texture atlas, with triangle_strip or triangles. iPhone opengl es

Question

Multiple places recommend using a texture atlas for performance. Apple suggest the function gltexcoordpointer. In my example I have a row of squares each one is given a random texture. I put all the random textures into the super-texture. Now the problem is I can't seem to create a texcoordarray. I can't find any information on how gltexcoordpointer assings the selected sub-texture to the vertex coords. The vertexes would ideally be drawn using triangle_strip, but triangles will work as well.

Answer 1

glTexCoordPointer如果你想渲染纹理，你必须使用压缩或其他方式，我认为。但是，如果您想在其 UV 坐标系内移动您的纹理，您可以随时完全自由地操作纹理坐标数组中的各个条目。我使用这样的功能：

- (void) shiftTextureUVY:(float)shift {

  textureVertices[1] += shift;
  textureVertices[3] += shift;
  textureVertices[5] += shift;
  textureVertices[7] += shift;

}
- (void) shiftTextureUVX:(float)shift {

  textureVertices[0] += shift;
  textureVertices[2] += shift;
  textureVertices[4] += shift;
  textureVertices[6] += shift;

}

制作一个基本TextureAtlas类，使用GL_TRIANGLE_STRIP. 我想你可能会变得非常时髦，并用类似的方法进行反射和扭曲。

Answer 2

gltexcoorpointer 以 1-1 的方式分配纹理坐标。所以我不得不画成三角形并重复许多顶点。我无法共享顶点的原因是共享顶点具有相同的纹理坐标。