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willy9532

How to Normal

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This is quite basic question. I am trying to draw 3d box with just 8 vertices in D3dIM. This can be possible when I call "DrawIndexedPrimitive()" 6 times(each call for each surface of box). Of course, I have 6 Index array which are pointing the vertices. // pDev : IDirect3DDevice7 // pVertices : vertex array which contains 8 vertice for box // pIndices : array of Indices which are pointing vertex // pIndices[0]: indices of vertices for Surface 0 of box // pIndices[1]: indices of vertices for Surface 1 of box for(int i=0; i<6; i++) { pDev->DrawIndexedPrimitive(D3DPT_TRIANGLESTRIP, D3DFVF_VERTEX, (LPVOID)pVertices, 8, pIndices, 4, D3DDP_WAIT); } But problem is normal vector.. Should I calculate normal vector whenever calling DrawIndexedPrimitive each time?

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NO!!!! Absolutely not. calculating normals takes a lot of work by the processor. precalculate your normals

<(o)>

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Thankyou...

Actual code is like the following...
Here You can see SetSideNormal() Function.
I don''t like to do like this...
Is there any way?
I need to save memory and consider performance...



WORD g_nBoxIndices[6][4] = { {0, 1, 3, 2}, {1, 5, 2, 6},
{7, 6, 4, 5}, {3, 7, 0, 4}, {3, 2, 7, 6}, {4, 5, 0, 1}};

float g_fBoxNormals[6][3] = { {0.0f, 0.0f, -1.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, {0.0f, -1.0f, 0.0f},
{1.0f, 0.0f, 0.0f}, {-1.0f, 0.0f, 0.0f} };


void SetSideNormal(D3DVERTEX *pVtx, int nSide)
{
for (int i=0; i<4; i++)
{
pVtx[g_nBoxIndices[nSide]].nx = g_fBoxNormals[nSide][0];
pVtx[g_nBoxIndices[nSide][i]].ny = g_fBoxNormals[nSide][1];
pVtx[g_nBoxIndices[nSide][i]].nz = g_fBoxNormals[nSide][2];
}
}


void DrawBox()
{
//...

for(int i=0; i<6; i++)
{
SetSideNormal(m_pBoxes[nBox]->pVertex, i);
pDev->DrawIndexedPrimitive(D3DPT_TRIANGLESTRIP, D3DFVF_VERTEX, (LPVOID)pBoxVertex, 8, g_nBoxIndices[i], 4, D3DDP_WAIT);
}
//...
}

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