In Java I create a frustum projection matrix via

Matrix.frustumM(projMatrix, 0, left, right, bottom top, near, far);

and a view matrix via

Matrix.setLookAtM(viewMatrix, 0,
                               0, 0, -2.5,  // eye position
                               0, 0, 0      // look position
                               0, -1, 0);   // up direction

My question is:

Which part of the frustum originates at the eye position? Is it the tip of the pyramid, or the centre of the near plane?

up vote 1 down vote accepted

The eye position is at the tip of the pyramid though the actual projection will end up on the near plane i.e the near plane will be your "screen"

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  • So if I had a world coordinate point at (0, 0, 0) and the camera was at (0, 0, 1) looking directly at (0, 0, 0), with a near distance of 1, then that (0, 0, 0) point should appear in the centre of the screen? – Antinous Dec 6 at 20:56
  • Not sure because it would be in the near plane – Hampus Dec 6 at 21:21

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