opengl glfrustum function implement

would somebody tells me how that glfrustum matrix generated? i know about that matrix can be set many ways, but wh开发者_StackOverflow中文版y that one? thanks

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would somebody tells me how that glfrustum matrix generated?

Read official glFrustrum documentation. It includes formula.

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i know about that matrix can be set many ways, but why that one

Because it defines exactly the portion of the space that is projected onto the plane: Connect the eye point with the four corners of the near plane (specified by left, right, top, bottom and nearVal). Then intersect the lines with the far plane to get the remaining four points of the frustum.