Directx issues

dpro · 03-23-2005, 02:54 PM

I haven't really seen any issues posted about this... however there is always a possibility of me misreading something.

In any event, I started working with vertex buffers and am now having a problem. When I click and drag on the screen I am creating rectangles (this is intended) then I record the position, relative to the client window and make sure these coordinates are passed to the vertex buffers. Then I finally render the rectangle on the screen, however with the transformed verticies (passing these to a customvertex struct I picked up from someone's code)...

Code:

struct CUSTOMVERTEX
	{
		FLOAT x, y, z, rhw; // The transformed position for the vertex
		DWORD color;        // The vertex color
	};

	// Our custom FVF, which describes our custom vertex structure
	#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)

I have found that the rectangle being drawn is usually offset as I go further in the y direction. I have added 2x2 rectangles to represent the position in the window according to windows GDI, but I notice they are off. At the top of the window they are almost dead on, but as I got further +y it gets worse.

Kinda looks like this at the bottom of the window.

instead its here -> ----------------
| |
topleft should be->x
...
|_________|

bottom right should be here -->x

Any ideas? Lemme know if you need a better explanation, thanks.

**Bubba** · 03-24-2005, 08:07 AM

You need to adjust for GDI and the way it is representing the graphics. GDI can use many many different types of mapping modes. MM_TEXT is what I think you want.

dpro · 03-24-2005, 12:30 PM

wow that totally did not format right at all hopefully that will help me, it was supposed to represent a square which was shifted up on the yu-axis buyt apparently I couldn't format that

dpro · 03-29-2005, 06:41 PM

Quote:

Originally Posted by Bubba

You need to adjust for GDI and the way it is representing the graphics. GDI can use many many different types of mapping modes. MM_TEXT is what I think you want.

Hmm I set the mapping mode to MM_TEXT, and tried a couple others, but its not working how I would have hoped.

When I set out my vertexbuffers, they are given (for right now anyway) fixed coordinates. For example I create a CRect..

Code:

CRect myRect(200, 100, 500, 400);

Then I get the buffers setup...

Code:

verticies[0].x  =  (float)myRect.left;
	verticies[0].y  =  (float)myRect.top;
	verticies[0].z  =  0.0f;
	verticies[0].rhw = 1.0f;
	verticies[0].tu =  0.0f;
	verticies[0].tv =  0.0f;

	verticies[1].x  =  (float)myRect.right;
	verticies[1].y  =  (float)myRect.top;
	verticies[1].z  =  0.0f;
	verticies[1].rhw = 1.0f;
	verticies[1].tu =  1.0f;
	verticies[1].tv =  0.0f;

	verticies[3].x  =  (float)myRect.right;
	verticies[3].y  =  (float)myRect.bottom;
	verticies[3].z  =  0.0f;
	verticies[3].rhw = 1.0f;
	verticies[3].tu =  1.0f;
	verticies[3].tv =  1.0f;

	verticies[2].x  =  (float)myRect.left;
	verticies[2].y  =  (float)myRect.bottom;
	verticies[2].z  =  0.0f;
	verticies[2].rhw = 1.0f;
	verticies[2].tu =  0.0f;
	verticies[2].tv =  1.0f;

and then try to render it...

I draw a rectangle in the ondraw function (yes I am using MFC for this), and whats rendered by direct3d and the GDI are a bit off. Most notably in the y-axis. Usually its almost bang-on with the x-axis. Getting a book on this as well, but its always nice to have help from outside sources as well

. Thanks again, and hopefully this explanation makes more sense than my previous one...

**Bubba** · 03-30-2005, 07:50 AM

Sounds like you are still using the wrong units for mapping. Make sure it is pixels and remember that the y aspect ratio will change as the size of the window changes. There are always less pixels in Y than X. This is probably what you are seeing.

The correct pixel aspect ratio for any given window barring field of view and all of that is:

AspectY=HorizPixels/VertPixels;

Now when you move vertically you must account for AspectY. Multiply all your y movements by AspectY and it should come out right.

dpro · 03-30-2005, 01:17 PM

Hmmm interesting, I set it to MM_TEXT, and it reports to me that I did set MM_TEXT.

I tried to use the aspecty, but either I am just totally missing your meaning, or I am doing it wrong. Basically I took the client width/height to get the aspect ratio, but its stretching the image instead of fitting it accordingly. I will attach two images which should help a lot more than words. I appreciate the help a lot

The red-blue box is the GDI indicating the rectangle I am trying to draw.

This is defined again as

Code:

CRect myRect(200, 100, 500, 400);

My directx setup is as follows...

Code:

g_pD3D = Direct3DCreate9( D3D_SDK_VERSION );

    D3DDISPLAYMODE d3ddm;

    g_pD3D->GetAdapterDisplayMode( D3DADAPTER_DEFAULT, &d3ddm );

    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory( &d3dpp, sizeof(d3dpp) );
	
    d3dpp.Windowed               = TRUE;
    d3dpp.SwapEffect             = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat       = d3ddm.Format;
    d3dpp.EnableAutoDepthStencil = TRUE;
    d3dpp.AutoDepthStencilFormat = D3DFMT_D16;
    d3dpp.PresentationInterval   = D3DPRESENT_INTERVAL_IMMEDIATE;

    g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, GetSafeHwnd(),
                          D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                          &d3dpp, &g_pd3dDevice );

	loadTexture();
	
	g_pd3dDevice->CreateVertexBuffer( 4*sizeof(Vertex), D3DUSAGE_WRITEONLY, 
                                      D3DFVF_CUSTOMVERTEX, D3DPOOL_DEFAULT, 
                                      &g_pVertexBuffer, NULL );
    void *pVertices = NULL;
	setupVerts();

    g_pVertexBuffer->Lock( 0, 0, (void**)&pVertices, 0 );
    memcpy( pVertices, verticies, sizeof(verticies) );
    g_pVertexBuffer->Unlock();

    D3DXMATRIX matProj;
    D3DXMatrixPerspectiveFovLH( &matProj, D3DXToRadian( 45.0f ), 
                                640.0f / 480.0f, 0.1f, 100.0f );
    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );

	g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, FALSE);

Dunno if that will help, but I would appeciate input. It shouldn't be this hard, or I am just thinking about it in the wrong way. Either way, pointers to tutorials or a good explanation is the best. Thanks again

**Bubba** · 03-30-2005, 01:53 PM

Then maybe the division I posted is backwards. Try PixelY*(height/width).

dpro · 03-30-2005, 01:58 PM

Tried that actually, it shrunk instead

I am not sure if I am just totally off, or if anyone has had this before at all... I'm using vertex buffers, but transformed coords, so it should not be a problem I wouldn't think...

03-23-2005, 02:54 PM	#1
dpro I am me, who else? Join Date: Oct 2002 Posts: 250	Directx issues I haven't really seen any issues posted about this... however there is always a possibility of me misreading something. In any event, I started working with vertex buffers and am now having a problem. When I click and drag on the screen I am creating rectangles (this is intended) then I record the position, relative to the client window and make sure these coordinates are passed to the vertex buffers. Then I finally render the rectangle on the screen, however with the transformed verticies (passing these to a customvertex struct I picked up from someone's code)... Code: struct CUSTOMVERTEX { FLOAT x, y, z, rhw; // The transformed position for the vertex DWORD color; // The vertex color }; // Our custom FVF, which describes our custom vertex structure #define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW\|D3DFVF_DIFFUSE) I have found that the rectangle being drawn is usually offset as I go further in the y direction. I have added 2x2 rectangles to represent the position in the window according to windows GDI, but I notice they are off. At the top of the window they are almost dead on, but as I got further +y it gets worse. Kinda looks like this at the bottom of the window. instead its here -> ---------------- \| \| topleft should be->x ... \|_________\| bottom right should be here -->x Any ideas? Lemme know if you need a better explanation, thanks.
dpro is offline

03-24-2005, 08:07 AM	#2
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,813	You need to adjust for GDI and the way it is representing the graphics. GDI can use many many different types of mapping modes. MM_TEXT is what I think you want. __________________ If you aim at everything you will hit something but you won't know what it is.
Bubba is offline

03-24-2005, 12:30 PM	#3
dpro I am me, who else? Join Date: Oct 2002 Posts: 250	wow that totally did not format right at all hopefully that will help me, it was supposed to represent a square which was shifted up on the yu-axis buyt apparently I couldn't format that
dpro is offline

03-30-2005, 07:50 AM	#5
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,813	Sounds like you are still using the wrong units for mapping. Make sure it is pixels and remember that the y aspect ratio will change as the size of the window changes. There are always less pixels in Y than X. This is probably what you are seeing. The correct pixel aspect ratio for any given window barring field of view and all of that is: AspectY=HorizPixels/VertPixels; Now when you move vertically you must account for AspectY. Multiply all your y movements by AspectY and it should come out right. __________________ If you aim at everything you will hit something but you won't know what it is.
Bubba is offline

03-30-2005, 01:53 PM	#7
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,813	Then maybe the division I posted is backwards. Try PixelY*(height/width). __________________ If you aim at everything you will hit something but you won't know what it is.
Bubba is offline

03-30-2005, 01:58 PM	#8
dpro I am me, who else? Join Date: Oct 2002 Posts: 250	Tried that actually, it shrunk instead I am not sure if I am just totally off, or if anyone has had this before at all... I'm using vertex buffers, but transformed coords, so it should not be a problem I wouldn't think...
dpro is offline

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