Poma

04-03-2005, 12:27 AM

There is a question about Frustom as follows

Ex. There is a flat ground and the coordinate of its 4 corner are

(4, 0, 4),(-4, 0, 4),(4, 0, -4),(-4, 0, -4),

I want to use glFrustom and set the

near = 1, far = 4,

top = 2, bottom = -2

right= 2, left = -2

after matrix calculation, the 4 points becomes

(2,0,-28/3,-4) (-2,0,-28/3,-4)

(2,0,4,4) (-2,0,4,4)

after homogenizaion :

(-0.5, 0, 7/3, 1) (0.5, 0, 7/3, 1)

(0.5, 0, 1, 1) (-0.5, 0, 1, 1)

I don't understand that can i use this 4 points to raster a correct ground?

Ex. There is a flat ground and the coordinate of its 4 corner are

(4, 0, 4),(-4, 0, 4),(4, 0, -4),(-4, 0, -4),

I want to use glFrustom and set the

near = 1, far = 4,

top = 2, bottom = -2

right= 2, left = -2

after matrix calculation, the 4 points becomes

(2,0,-28/3,-4) (-2,0,-28/3,-4)

(2,0,4,4) (-2,0,4,4)

after homogenizaion :

(-0.5, 0, 7/3, 1) (0.5, 0, 7/3, 1)

(0.5, 0, 1, 1) (-0.5, 0, 1, 1)

I don't understand that can i use this 4 points to raster a correct ground?