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POReading a openGL ES texture to a raw array
 

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  1. POReading a openGL ES texture to a raw array
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    <p>I'm trying to get the bytes from a RGBA texture in openGL ES. I think I'm trying to imitate <code>glGetTexImage</code> from vanilla openGL. As is right now, the pixels are all nil, from the call to <code>glClear</code>, not the texture data I'm looking for.</p> <p>This is a method in a category extending SPTexture from Sparrow Framework.</p> <pre><code>-(NSMutableData *) getPixelsFromTexture { GLsizei width = (GLsizei) self.width; GLsizei height = (GLsizei) self.height; GLint oldBind = 0; glGetIntegerv(GL_TEXTURE_BINDING_2D, &amp;oldBind); glBindTexture(GL_TEXTURE_2D, self.textureID); GLuint fbo[1]; glGenFramebuffersOES(1, fbo); glBindFramebufferOES(GL_FRAMEBUFFER_OES, fbo[0]); GLuint rbo[1]; glGenRenderbuffersOES(1, rbo); glBindRenderbufferOES(GL_RENDERBUFFER_OES, rbo[0]); glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_RGBA4_OES, width, height); glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, rbo[0]); GLenum status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES); if (status != GL_FRAMEBUFFER_COMPLETE_OES) { NSLog(@"Incomplete FBO"); } // draw static float texCoords[8] = { 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f }; static float vertexCoords[8] = { -1.0f, -1.0f, 1-.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f }; glMatrixMode (GL_PROJECTION); glPushMatrix(); glLoadIdentity (); glOrthof(0.0f, self.width, self.height, 0.0f, 0.0f, 1.0f); glMatrixMode (GL_MODELVIEW); glPushMatrix(); glLoadIdentity(); glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); glTexCoordPointer(2, GL_FLOAT, 0, texCoords); glVertexPointer(2, GL_FLOAT, 0, vertexCoords); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glDisableClientState(GL_VERTEX_ARRAY); glPopMatrix(); glMatrixMode(GL_PROJECTION); glPopMatrix(); // end draw GLsizei count = width * height * 4; GLubyte * pixels = (GLubyte *)malloc((sizeof(GLubyte) * count)); glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels); glBindRenderbufferOES(GL_RENDERBUFFER_OES, 0); glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); glBindTexture(GL_TEXTURE_2D, oldBind); glDeleteRenderbuffersOES(1, rbo); glDeleteFramebuffersOES(1, fbo); return [NSMutableData dataWithBytes:pixels length:count]; } </code></pre> <p>What am I doing wrong?</p>
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    2. COAdded a description of the issue. Sorry and thanks.
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