several problems with my terrain generator

Sheep · 2002-05-06T19:34:44

Hello everyone. I have recently been working on a terrain generator, and have finally gotten something up that somewhat resembles terrain ( not quite ). However, now I seem to be getting less than one frame per second (average: 0.014 fps). I cant seem to think why it would do this. The only thing the debugger gives is this: First-chance exception in Test.exe (GDI32.DLL): 0xC0000005: Access Violation. Could that be the cause? The debugger doesnt tell me what line its on, so I dont know whats causing it. Here is the relevant code: HRESULT CTerrain::FillVB( LPDIRECT3DDEVICE8 pd3dDevice ) { if( pd3dDevice == NULL ) return E_FAIL; // create the vertices DWORD count = 0L; for ( float x = 0; x < m_nWidth; x ++ ) { for ( float z = 0; z < m_nHeight; z ++ ) { m_pMapIndex[count].p.x = x*2; m_pMapIndex[count].p.y = GetCell( x, z ); m_pMapIndex[count].p.z = z*2; m_pMapIndex[count].tu0 = ((x)/m_nWidth); m_pMapIndex[count].tv0 = 1.0f-((z)/m_nHeight); count++; } } if( FAILED( pd3dDevice->CreateVertexBuffer(m_dwNumVerts * sizeof(TERRAIN_VERT), 0, D3DFVF_TERRAIN, D3DPOOL_DEFAULT, &m_pVB ) ) ) { return E_FAIL; } // Fill vertex buffer VOID* pVertices; if( FAILED( m_pVB->Lock( 0, sizeof(TERRAIN_VERT) * m_dwNumVerts, (BYTE**)&pVertices, 0 ) ) ) { return E_FAIL; } memcpy(pVertices, m_pMapIndex, sizeof(TERRAIN_VERT) * m_dwNumVerts); m_pVB->Unlock(); return S_OK; } HRESULT CTerrain::FillIB( LPDIRECT3DDEVICE8 pd3dDevice ) { if( pd3dDevice == NULL ) return E_FAIL; m_dwNumTris = m_nWidth * m_nHeight; m_pdwIndices = new DWORD[m_dwNumTris * 6]; DWORD count = 0L; for ( int z = 0; z < m_nHeight; z ++ ) { for (int x = 0; x < m_nWidth; x ++) { // create vertex index from co-ordinate WORD index= x + (z * m_nWidth ); m_pdwIndices[count]=index; m_pdwIndices[count+1]=index+m_nWidth; m_pdwIndices[count+2]=index+1; count+=3; m_pdwIndices[count]=index+m_nWidth; m_pdwIndices[count+1]=index+m_nWidth+1; m_pdwIndices[count+2]=index+1; count+=3; } } // Triangle indexes if( FAILED( pd3dDevice->CreateIndexBuffer( m_dwNumTris*sizeof(DWORD)*3, D3DUSAGE_WRITEONLY, D3DFMT_INDEX16, D3DPOOL_DEFAULT, &m_pIB) ) ) { return E_FAIL; } VOID *pIndices; if( FAILED( m_pIB->Lock( 0, m_dwNumTris*sizeof(WORD)*3, (BYTE**)&pIndices, 0 ) ) ) return E_FAIL; memcpy(pIndices,m_pdwIndices,sizeof(WORD)*m_dwNumTris*3); m_pIB->Unlock(); return S_OK; } and for rendering: pd3dDevice->SetTexture( 0, m_pTexture ); pd3dDevice->SetStreamSource(0, m_pVB, sizeof(TERRAIN_VERT)); pd3dDevice->SetVertexShader(D3DFVF_TERRAIN); pd3dDevice->SetIndices(m_pIB, 0 ); pd3dDevice->DrawIndexedPrimitive( D3DPT_TRIANGLELIST, 0, m_dwNumVerts, 0, m_dwNumTris ); Any ideas? Thanks. [edited by - Sheep on May 5, 2002 12:54:57 PM]

Pactuul

122

May 05, 2002 01:13 PM

well I think the reason the terrain seems to be a triangle is that your rendering only half or a part of your triangles.

This is probably again related to your use of the array to keep the vertices. It may be related to the way your accessing the arrays that would be causing the stretched triangle and only part of the terrain being render (the "rectangluar" effect)

I would look over and make sure your parsing through the array of vertices correctly, and also make sure your using the correct size for each vertex structure(x,y,z, normal, extra info) .

-Pac "The thing I like about friends in my classes is that they can't access my private members directly." "When listening to some one tell about their problem (whether it's code or not), don't listen to what went right or wrong, but what they assumed....."

Pactuul

122

May 05, 2002 01:29 PM

Looking over your code....it seems correct
Except I notice your doubling the size of the terrain by putting x*2 and z*2 for the x and z locations. BUT on your texture coordinates, your only using z and x as in :

m_pMapIndex[count].tu0 = ((x)/m_nWidth);
m_pMapIndex[count].tv0 = 1.0f-((z)/m_nHeight);

you need to double those values too. But that shouldn''t make a big difference in the look

also in FillIB(), the line:
m_dwNumTris = m_nWidth * m_nHeight;

is not correct...if you have a 3x3 grid of points you will have 8 triangles not 9 (using your formula). The acutal number of triangles is:

m_dwNumTris = (m_nWidth-1) * (m_nHeight-1) * 2

That would probably be way your only rendering half the terrain.

Hope that helps.

-Pac "The thing I like about friends in my classes is that they can't access my private members directly." "When listening to some one tell about their problem (whether it's code or not), don't listen to what went right or wrong, but what they assumed....."

Sheep

152

Author

May 05, 2002 01:46 PM

Sorry if I wasnt clear about that Pactuul...I emailed you some screenshots of whats going on...

EDIT: Pactuul you posted before i sent the email...i'll try that.

[edited by - Sheep on May 5, 2002 2:51:27 PM]

Sheep

152

Author

May 05, 2002 06:50 PM

hahaha! thanks alot! the triangle is still sticking out, but now the terrain is sized correctly....somewhat...when I do the number of tri''s * 2, it wider, but still longer...if I multiply by 6 its even more square like...any ideas why this happens?

Pactuul

122

May 06, 2002 12:07 AM

that triangle sticking out is where I think GetCell(x,z) is returning an invalid number. Since the triangle looks like its at the end corner, it might be near the end of the array, so make sure your generating correct heights for ALL those points, cause I think you might accidently be leaving off the last one.

-Pac "The thing I like about friends in my classes is that they can't access my private members directly." "When listening to some one tell about their problem (whether it's code or not), don't listen to what went right or wrong, but what they assumed....."

Sheep

152

Author

May 06, 2002 10:01 AM

Wow! You were right! It was in the GetCell(x,y) function! but now I still have my problem with this:

m_dwNumTris = ((m_nWidth-1) * (m_nHeight-1)) * 2;

That makes the terrain more square-like than before, but not quite. Then I tryed multiplying it by 6 instead of 2 and it became even more square like, but not quite. What do I have to do to make it a square??? Thanks for your help so far...

Pactuul

122

May 06, 2002 10:28 AM

hmmm well I think that algo isn't quite right either:

m_dwNumTris = ((m_nWidth-1) * (m_nHeight-1)) * 2;

thinking about it: try dropping the -1's on the equation.

Better YET: to definately make sure, in your FillIB() do this

      	   for ( int z = 0;	z <	m_nHeight; z ++	)	   {			 		   for (int	x =	0; x < m_nWidth; x ++)				   {						   // create vertex	index from co-ordinate								   WORD	index= x + (z *	m_nWidth );								   m_pdwIndices[count]=index;								   m_pdwIndices[count+1]=index+m_nWidth;			 			   m_pdwIndices[count+2]=index+1;								   count+=3;										   m_pdwIndices[count]=index+m_nWidth;								   m_pdwIndices[count+1]=index+m_nWidth+1;				   			   m_pdwIndices[count+2]=index+1;								   count+=3;							   m_dwNumTris += 2;				   //change!				   }		   }

And of course delete the other m_dwNumTris code that modifies it.

[edited by - Pactuul on May 6, 2002 11:32:27 AM]

-Pac "The thing I like about friends in my classes is that they can't access my private members directly." "When listening to some one tell about their problem (whether it's code or not), don't listen to what went right or wrong, but what they assumed....."

Sheep

152

Author

May 06, 2002 07:34 PM

Argghhh...my arrays keep overflowing

...any other ideas?

several problems with my terrain generator

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several problems with my terrain generator

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