|
no, but the division is just to remap the values into normalised screen
space coords (which basically comes down to the impementation of the
specific context in which you need to use the results).
the entire transformation is handled by the matricies.
btw, i'm sure the matrix representation of your dog is pretty ugly ;)
kim aldis wrote:
But the division isn't part of the matrix,no?
Would you give me the matrix representation of my dog? ;)
-----Original Message-----
From: owner-xsi(at)Softimage.COM
[mailto:owner-xsi(at)Softimage.COM] On Behalf Of Brent McPherson
Sent: 05-October-2005 13:53
To: XSI(at)Softimage.COM
Subject: RE: Camera projection matrix
You can represent everything by a 4x4 matrix.
In hardware it is broken down into two stages because they
need to clipping to the view volume. In software when
transforming points between screen <-> world space clipping
is not necessary so I always like to use a single 4x4 matrix
that takes points directly to screen space.
In this scenario a world point is represented as a 4D point
(x,y,z,1) which gets transformed (by the 4x4 projection
matrix) matrix to (x',y',z',w). All that remains is a simple
division by w to get the final screen coordinates (x'/w, y'/w)
--
Brent
-----Original Message-----
From: owner-xsi(at)Softimage.COM
[mailto:owner-xsi(at)Softimage.COM] On Behalf Of kim aldis
Sent: 05 October 2005 12:49
To: XSI(at)Softimage.COM
Subject: RE: Camera projection matrix
But surely the projection isn't a matrix. The world to camera
transform can be represented as a matrix but the perspective
divide can't, can it? Then there's the view frustrum clip ...
-----Original Message-----
From: owner-xsi(at)Softimage.COM
[mailto:owner-xsi(at)Softimage.COM] On Behalf Of Martin Bélanger
Sent: 04-October-2005 16:52
To: XSI(at)Softimage.COM
Subject: RE: Camera projection matrix
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
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in
body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in
body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following
text in body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following
text in body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
unsubscribe xsi
|
