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Setting a viewport..?

Started by Fyyar Nov 2, 2002 at 2:32 AM 0 replies 300+ views

Original Post

Nov 2, 2002 at 2:32 AM

Hello all! I have a simple question with a simple (I hope) answer. If I use the following code.. ("borrowed" and modified from another post)

  
D3DXMATRIX mat;	
//Projection Matrix	

D3DXMatrixOrthoLH(&mat,	1.0f, 1.0f, 0.0f, 1.0f);
m_pDevice->SetTransform(D3DTS_PROJECTION, &mat);

//World Matrix	

D3DXMatrixIdentity(&mat);	
m_pDevice->SetTransform(D3DTS_WORLD, &mat);	

//View Matrix	

D3DXMatrixLookAtLH(&mat, &D3DXVECTOR3(0.0f, 0.0f, -0.5f), &D3DXVECTOR3(0.0f, 0.0f, 0.0f), &D3DXVECTOR3(0.0f, 1.0f, 0.0f));
m_pDevice->SetTransform(D3DTS_VIEW, &mat);

.. I get a situation where the upper left corner has coords. (-0.5,0.5) and the lower right corner has (0.5,-0.5). However, I want the upper left corner to have coords. (0.0,0.0) and the lower right (1.0,1.0). How do I do this?

bratsj

Nov 2, 2002 at 4:35 AM

The first vector of LookAtLH is your camera position.
The second is the point you are looking at.

By moving both these vectors (points really) 0.5 along
the x-axis and 0.5 down the y-axis (negative), your
resulting screen coordinates should meet your requirement.

thus:

D3DXMatrixLookAtLH(&mat, &D3DXVECTOR3(0.0f, 0.0f, -0.5f), &D3DXVECTOR3(0.0f, 0.0f, 0.0f), &D3DXVECTOR3(0.0f, 1.0f, 0.0f));

should be:

D3DXMatrixLookAtLH(&mat, &D3DXVECTOR3(0.5f, -0.5f, -0.5f), &D3DXVECTOR3(0.5f, -0.5f, 0.0f), &D3DXVECTOR3(0.0f, 1.0f, 0.0f));

Left-handed and right-handed orientation sometimes throws me
off though, so if you end up in the wrong quadrant (like
Voyager), just change the sign of the x or the y or both :-)

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