RE: Camera projection matrix

[Martin Bélanger <martinb(at)Softimage.COM>]

Hello Harry,

You can simply calculate it yourself using these useful code.

set oCamProj = XSIMath.CreateMatrix4
BuildPerspMatrix oCamProj, in_oCam

' =============================================
' Builds the perspective transformation matrix
' from a camera.
' - Glen Fraser (Nov 2002)
' =============================================
sub BuildPerspMatrix( io_mat, in_oCam )
	'
	' Build the projection matrix
	'
	if in_oCam.projplane.value then
		MatrixFromPPlane io_mat, in_oCam
	else
		MatrixFromSimpleFOV io_mat, in_oCam
	end if
end sub
' =============================================
' Computes the camera projection matrix when
' only the FOV parameter is used (the "normal" case).
' - Glen Fraser (Nov 2002)
' =============================================
sub MatrixFromSimpleFOV( io_mat, in_oCam )
	dim fovTan, aspect, near, far, width, height
	
	fovTan = tan( XSIMath.DegreesToRadians( in_oCam.fov.value ) * 0.5 )
	aspect = in_oCam.aspect.value
	near = in_oCam.near.value
	far = in_oCam.far.value
	if in_oCam.fovtype.value = 1 then
		width = fovTan
		height = fovTan / aspect
	else
		width = aspect * fovTan
		height = fovTan
	end if
	io_mat.Set 1 / width, 0, 0, 0, _
				0, 1 / height, 0, 0, _
				0, 0, -(far+near)/(far-near), -1, _
				0, 0, -2*near*far/(far-near), 0
end sub

' =============================================
' Computes the camera projection matrix when
' the "projection plane" parameters are used.
' - Glen Fraser (Nov 2002)
' =============================================
sub MatrixFromPPlane( io_mat, in_oCam )
	dim cx, cy, focal, near, far, width, height

	near = in_oCam.near.value
	far = in_oCam.far.value
	focal = in_oCam.projplanedist.value / 25.4 'convert to inches
	width = in_oCam.projplanewidth.value * near / focal
	height = in_oCam.projplaneheight.value * near / focal
	cx = in_oCam.projplaneoffx.value * near / focal
	cy = in_oCam.projplaneoffy.value * near / focal
	
	io_mat.Set 2 * near / width, 0, 0, 0, _
				0, 2 * near / height, 0, 0, _
				2 * cx / width, 2 * cy / height, -(far+near)/(far-near), -1, _
				0, 0, -2*near*far/(far-near), 0
end sub 


-Martin
-----Original Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Harry BARDAK
Sent: Tuesday, October 04, 2005 11:07 AM
To: XSI(at)Softimage.COM
Subject: Camera projection matrix

hi everyone

Is there any method to get the camera projection matrix in script ?
I m a bit lost in the script reference guide.

Thanks.

harry


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