Texturing a Sphere

Graphics and GPU Programming Programming

Started by Todd Casey July 13, 2000 10:32 PM

2 comments, last by Todd Casey 23 years, 9 months ago

Todd Casey

122

Author

July 13, 2000 10:32 PM

What is the best way to handle texturing a sphere? Thanks for any info. Todd

Syzygy

122

July 13, 2000 11:40 PM

Here''s some code to build a sphere with texture coordinates in the verticies. (It''s stolen directly from the DX8 bumpearth sample code, so I take no blame or credit for it.)

        // Get the World-View(WV) matrix set    D3DXMATRIX matWorld, matView, matWorldView;    m_pd3dDevice->GetTransform( D3DTS_WORLD, &matWorld );    m_pd3dDevice->GetTransform( D3DTS_VIEW,  &matView );    D3DXMatrixMultiply( &matWorldView, &matWorld, &matView );    // Lock the vertex buffer    BUMPVERTEX* vtx;    m_pEarthVB->Lock( 0, 0, (BYTE**)&vtx, 0 );    // Establish constants used in sphere generation    DWORD dwNumSphereRings    = m_bHighTesselation ? 15 :  5;    DWORD dwNumSphereSegments = m_bHighTesselation ? 30 : 10;    FLOAT fDeltaRingAngle = ( D3DX_PI / dwNumSphereRings );    FLOAT fDeltaSegAngle  = ( 2.0f * D3DX_PI / dwNumSphereSegments );    D3DXVECTOR4 vT;    FLOAT fScale;    // Generate the group of rings for the sphere    for( DWORD ring = 0; ring < dwNumSphereRings; ring++ )    {            FLOAT r0 = sinf( (ring+0) * fDeltaRingAngle );        FLOAT r1 = sinf( (ring+1) * fDeltaRingAngle );        FLOAT y0 = cosf( (ring+0) * fDeltaRingAngle );        FLOAT y1 = cosf( (ring+1) * fDeltaRingAngle );        // Generate the group of segments for the current ring        for( DWORD seg = 0; seg < (dwNumSphereSegments+1); seg++ )        {            FLOAT x0 =  r0 * sinf( seg * fDeltaSegAngle );            FLOAT z0 =  r0 * cosf( seg * fDeltaSegAngle );            FLOAT x1 =  r1 * sinf( seg * fDeltaSegAngle );            FLOAT z1 =  r1 * cosf( seg * fDeltaSegAngle );            // Add two vertices to the strip which makes up the sphere            (*vtx).p   = (*vtx).n   = D3DXVECTOR3(x0,y0,z0);            (*vtx).tu1 = (*vtx).tu2 = -((FLOAT)seg)/dwNumSphereSegments;            (*vtx).tv1 = (*vtx).tv2 = (ring+0)/(FLOAT)dwNumSphereRings;			// Use the transformed normal to generate texture coords            D3DXVec3Transform( &vT, &(*vtx).n, &matWorldView );            fScale = 1.37f / D3DXVec4Length( &vT );            (*vtx).tu1 = 0.5f + fScale*vT.x;            (*vtx).tv1 = 0.5f - fScale*vT.y;            vtx++;            (*vtx).p   = (*vtx).n   = D3DXVECTOR3(x1,y1,z1);            (*vtx).tu1 = (*vtx).tu2 = -((FLOAT)seg)/dwNumSphereSegments;            (*vtx).tv1 = (*vtx).tv2 = (ring+1)/(FLOAT)dwNumSphereRings;            // Use the transformed normal to generate texture coords            D3DXVec3Transform( &vT, &(*vtx).n, &matWorldView );            fScale = 1.37f / D3DXVec4Length( &vT );            (*vtx).tu1 = 0.5f + fScale*vT.x;            (*vtx).tv1 = 0.5f - fScale*vT.y;            vtx++;        }    }    m_pEarthVB->Unlock();