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Scaling without D3DX



Scaling without D3DX
Here is our replacement for D3DXMatrixScaling:
// Procedure: dhMatrixScaling
// Whazzit:Prepares a Matrix to scale an object along the X, Y, and Z axis.
D3DXMATRIX *dhMatrixScaling(D3DXMATRIX *pOut, float sx,float sy, float sz){

   pOut->_11 = sx;      pOut->_12 =  0.0f;   pOut->_13 = 0.0f;    pOut->_14 = 0.0f;
   pOut->_21 = 0.0f;    pOut->_22 =  sy;     pOut->_23 = 0.0f;    pOut->_24 = 0.0f;
   pOut->_31 = 0.0f;    pOut->_32 =  0.0f;   pOut->_33 = sz;      pOut->_34 = 0.0f;
   pOut->_41 = 0.0f;    pOut->_42 =  0.0f;   pOut->_43 = 0.0f;    pOut->_44 = 1.0f;

   return pOut;
}

Here is our new render() function:
// Function: render
// Whazzit:Draws a triangle and then presents the results.
void render(void){
D3DXMATRIX matWorld;
D3DXMATRIX trans_matrix;   //Our translation matrix
D3DXMATRIX scale_matrix;


   //Clear the buffer to our new colour.
   g_d3d_device->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,0), 1.0f, 0 );

   //Notify the device that we're ready to render
   if(SUCCEEDED(g_d3d_device->BeginScene())){

      //Vertex shaders are a complex topic, but you can do some amazing things with them
      //For this example we're not creating one, so we tell Direct3D that we're just
      //using a plain vertex format.
      g_d3d_device->SetVertexShader(D3D8T_CUSTOMVERTEX);

      //D3D's rendering functions read from streams.  Here we tell D3D that the
      //VB we created for our triangle is the stream it should read from.
      g_d3d_device->SetStreamSource(0,g_vb,sizeof(my_vertex));

      //Big triangle off to the right
      dhMatrixScaling(&scale_matrix,2.0f,2.0f,2.0f);
      D3DXMatrixTranslation(&trans_matrix,2.0,0.0f,0.0f);
      D3DXMatrixMultiply(&matWorld,&scale_matrix,&trans_matrix);
      g_d3d_device->SetTransform(D3DTS_WORLD,&matWorld );
      g_d3d_device->DrawPrimitive(D3DPT_TRIANGLELIST,0,1);

      //Small triangle off to the left
      dhMatrixScaling(&scale_matrix,0.5f,0.5f,0.5f);
      D3DXMatrixTranslation(&trans_matrix,-2.0,0.0f,0.0f);
      D3DXMatrixMultiply(&matWorld,&scale_matrix,&trans_matrix);
      g_d3d_device->SetTransform(D3DTS_WORLD,&matWorld );
      g_d3d_device->DrawPrimitive(D3DPT_TRIANGLELIST,0,1);

      //Normal triangle in the center
      D3DXMatrixIdentity(&matWorld);
      g_d3d_device->SetTransform(D3DTS_WORLD,&matWorld );
      g_d3d_device->DrawPrimitive(D3DPT_TRIANGLELIST,0,1);


      //Notify the device that we're finished rendering for this frame
      g_d3d_device->EndScene();
   }

   //Show the results
   g_d3d_device->Present( NULL, NULL, NULL, NULL );

}