title: EGLImages with renderbuffer as source sibling and texture as target sibling
body: <p>I am trying to setup an <code>EGLImage</code> where the source sibling is a <code>GL_RENDERBUFFER</code> (the <code>EGLClientBuffer</code> specified as an argument to <code>eglCreateImageKHR</code>). In another context, I create a <code>GL_TEXTURE_2D</code> and specify it as the target sibling of the <code>EGLImage</code> by using <code>glEGLImageTargetTexture2DOES</code>. Unfortunately, the latter call leads to a <code>GL_INVALID_OPERATION</code>. If both the source and target siblings are <code>GL_TEXTURE_2D</code>'s, the setup works like a charm.</p>
  
  <p>From my reading of the specification, this should be a permissable operation. It is also possible that my reduced test case has some other orthogonal issue. Though I doubt this since the setup works fine when both the source and target siblings are <code>GL_TEXTURE_2D</code>'s. However, if this were the issue (and this kind of usage of <code>EGLImage</code>s was permissable), what could be the possible issue that may lead to to a <code>GL_INVALID_OPERATION</code>. Or am I just mistaken in my interpretation of the specification?</p>
  
  <p>Referenced Extensions:</p>
  
  <p><a href="http://www.khronos.org/registry/gles/extensions/OES/OES_EGL_image.txt" rel="nofollow">http://www.khronos.org/registry/gles/extensions/OES/OES_EGL_image.txt</a></p>
  
  <p><a href="http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_image_base.txt" rel="nofollow">http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_image_base.txt</a></p>
  
  <p>Clarifications:</p>
  
  <ul>
  <li>I do check for the presence of all extensions in the specification (<code>EGL_KHR_image</code>, <code>EGL_KHR_image_base</code>, <code>EGL_KHR_gl_texture_2D_image</code>, <code>EGL_KHR_gl_renderbuffer_image</code>, etc..).</li>
  <li>I also realize that there may be differences in the internal format of the EGLImage when I am using a <code>GL_RENDERBUFFER</code> vs a <code>GL_TEXTURE_2D</code> as the source. So I tried using the <code>OES_EGL_image_external</code> extension first with the texture as the source and then the renderbuffer. The texture works fine as always, the same <code>GL_INVALID_OPERATION</code> for the renderbuffer. Using external images when binding makes no difference to the error generated.</li>
  <li>Both GL and EGL errors are checked after each call.</li>
  </ul>