frustum(left, right, bottom, top, zNear, zFar)-
A frustum is simply a pyramid, with its tip cut off. In this kind of projection, the viewer’s eye is placed at the tip of the pyramid, the other six planes act as the clipping planes. So, anything inside the clipping planes visible, and anything outside is not visible.
It is similar to glFrustum, but it replaces the current projection matrix with the new frustum projection matrix, whereas in glFrustum, which is a function of OpenGL, it multiplies the new frustum projection matrix with the current projection matrix.
Arguments -
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left - The coordinate for the left-vertical clipping plane.
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right - The coordinate for the right-vertical clipping plane.
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bottom - The coordinate for the bottom-horizontal clipping plane.
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top - The coordinate for the bottom-horizontal clipping plane.
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zNear - The distances to the near-depth clipping plane. Must be positive.
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zFar- The distances to the far-depth clipping planes. Must be positive.