The Easyest DirectX Question i Ever hope to ask

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rifter1818

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Ok this is a simple one, i want to use LeftHanded CC
View
CamPos 0,0,-100
CamTar 0,0,0
CamUp 0,1,0
Now how do i get my projection matric such that (on a 1024x768 resolution)
0,0,0 in the world is the center of the screen
-512, 384 ,0 is top left of screen
512, 384 ,0 is top right of screen
-512, -384,0 is bottom left of screen
512 , -384,0 is bottom right of screen
Really simple question but i really dont know how to fine tune my projection matrix (at least i think thats what i need to modify)
And before you as the question yes i know about transformed Vertices and all that.... Thanks in advance
 
rifter1818 said:
Ok this is a simple one, i want to use LeftHanded CC
View
CamPos 0,0,-100
CamTar 0,0,0
CamUp 0,1,0
Now how do i get my projection matric such that (on a 1024x768 resolution)
0,0,0 in the world is the center of the screen
-512, 384 ,0 is top left of screen
512, 384 ,0 is top right of screen
-512, -384,0 is bottom left of screen
512 , -384,0 is bottom right of screen
Really simple question but i really dont know how to fine tune my projection matrix (at least i think thats what i need to modify)
And before you as the question yes i know about transformed Vertices and all that.... Thanks in advance
Click to expand...
im not too sure if you want to use a projection matrix for that..
d3ddev.transform.view = OrthoLH(1024,768, znearplane,zfarplane)
would do what you're asking

OrthoOffCenterLH would specify the bounds like (IIRC):
(left , right, bottom, top, znear,zfar)
like what you're asking for. (and with the arguments that you provided, the center = 0,0,0

but OrthoLH would make your 'center point' 0,0,0
its basically:

left = -width/2
right = width/2
top = -height/2
bottom = height/2


isnt the LookAt matrix masinly for 3d games?
here's my tip
in 2d: i transform the world, and set the view = orthoLH
in 3d: i dont worry aobut my center point, so my view = LookAt, and projection = ..(crap i completely forgot lol - its like PerspectiveFOVLH or something)

pent
 
Are you sure?

d3d.Dev.Transform.View = Matrix.OrthoOffCenterLH(-512,512,-384,384,-50,0);
d3d.Dev.Transform.Projection = Matrix.PerspectiveLH(1024,768,-50,0);

Seems a little redundant to have Projection and View so simular and doesnt set campos,camtar,camup anywhere?!


Edit
After Testing doesnt seem to work, btw which Matrix makes it 10x larger in x,y?
Matrix.Scaling(10,10,1)
Matrix.Scaling(1/10,1/10,1)
Never Mind Problem was my cull mode Thanks Pent.
 
Last edited:
you're doing 3d right?
hmm,
ok, to set the center point to 0,0,0 - you'd have to set the camTarget to 0,0,0.. beucase that point will be the center of the screen

so just do
d3ddev.transform.view = matrix.lookatlh(campos, new vector3(0,0,0), new vector3(0,1,0)
d3ddev.transform.projection = matrix.perspectiveFOVLH( math.pi/4, 1, -50,0)
'math.pi / 4 is 45 degrees - so you can see "45 degrees around you",
the "1" represents the Aspect Ratio: most TV's use 16:9 which is widescreen (just type in 1.777 to get 16:9)

im not sure what PerspectiveLH is though
i beleive taht matrix.scaling (10,10,1) makes it 10x larger :)

pent
 
just wanna make a quick comment:
i dont think my reply was very clear lol

u said u want to makethe center point (0,0,0). in order to do that, just set the cameraTarget (0,0,0). becuase the cameraTarget is what you're looking at, and that point is the center of the screen

also, the greater the aspect ratio, the wider the objects will seem to appear

pent
 
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