使用 OpenGL ES 在 iPhone 上渲染到立方体贴图

Question

I'm trying to generate dynamic cube map on the iPhone using this code:

GLuint textureCubeMap;
glGenTextures(1, &textureCubeMap);
glBindTexture(GL_TEXTURE_CUBE_MAP, textureCubeMap);

for (int i = 0; i < 6; i++) {
    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, 256, 256, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, 0);
}

GLuint framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, textureCubeMap, 0);

GLenum framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if (framebufferStatus == GL_FRAMEBUFFER_UNSUPPORTED) {
    Log("Unsupported");
} else if (framebufferStatus == GL_FRAMEBUFFER_COMPLETE) {
    Log("All is OK");
}

When I'm running this code on iOS simulator, I see All is OK message in console.
But running on iPhone 5 with iOS 7 prints Unsupported message. As I understand iPhone does not support rendering to cube map. But I know this is possible because I saw the game with such effect. So my question is: What is the correct way to generate dynamic cube map on the iPhone using OpenGL ES ?

Answer 1

Try changing the call to the following:

glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, 256, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);

Hope this helps.