glReadPixels problem
Author
I'm trying to use glReadPixels to read the depth of the pixel at a particular window coordinate,
The problem that winZ is always 1.0
I'm calling the following code after rendering my scene. Any common errors anyone can think of? glGetError() returns GL_NO_ERROR
int winX = 400; // just for example
int winY = 300; // just for example
GLfloat winZ;
glGetIntegerv(GL_VIEWPORT, viewport);
glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
glGetDoublev(GL_PROJECTION_MATRIX, projection);
winY = viewport[3] - winY;
glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
Make sure
- you have a RC attached to a HDC (on Windows)
- you do some rendering before the query
- you have your zBuffer enabled
- you don't perform a SwapBuffers before the query
(or you have PFD_SWAP_COPY set)
- your viewport is at least 400x300 in size
- you have a RC attached to a HDC (on Windows)
- you do some rendering before the query
- you have your zBuffer enabled
- you don't perform a SwapBuffers before the query
(or you have PFD_SWAP_COPY set)
- your viewport is at least 400x300 in size
Author
Okay... It's not returning 1.0 but more like 0.98...
However, this is as small as it gets. Should it not be returning a number closer to 0 for the closer the pixels are to the camera? (if that makes sense?)
However, this is as small as it gets. Should it not be returning a number closer to 0 for the closer the pixels are to the camera? (if that makes sense?)
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