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BlackBox

Rendering the Light Frustum

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1) make a projection matrix for the light with gluPerspective()

2) make a modelview matrix for the light with gluLookAt()

3) combine the projection and modelview matrices to get the clipping planes of your light's frustum.

4) get the vertices of the frustum by finding the intersection point of 3 planes

5) display the vertices with lines in opengl. You don't have to draw the up and bottom plane.

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Quote:
Original post by godmodder
1) make a projection matrix for the light with gluPerspective()

2) make a modelview matrix for the light with gluLookAt()

3) combine the projection and modelview matrices to get the clipping planes of your light's frustum.

4) get the vertices of the frustum by finding the intersection point of 3 planes

5) display the vertices with lines in opengl. You don't have to draw the up and bottom plane.


Thanks I will give it a try!.



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multiply the 8 verts of a box (-1,-1,-1)->(1,1,1) by the inverse of the matrix resulting from the lights proj*mv (or u might wanna inverse them first)

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