 Z Rotations without D3DX Here is our replacement for D3DXMatrixRotationZ: ```// Procedure: dhMatrixRotationZ // Whazzit:Given an angle (in radians), produces a rotation matrix // to perform that transformation. D3DXMATRIX *dhMatrixRotationZ(D3DXMATRIX *pOut, float angle ){ float my_sin, my_cos; my_sin=(float)sin(angle); my_cos=(float)cos(angle); pOut->_11 = my_cos; pOut->_12 = my_sin; pOut->_13 = 0.0f; pOut->_14 = 0.0f; pOut->_21 = -my_sin; pOut->_22 = my_cos; pOut->_23 = 0.0f; pOut->_24 = 0.0f; pOut->_31 = 0.0f; pOut->_32 = 0.0f; pOut->_33 = 1.0f; 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 which shows that our function produces results identical to the D3DX version. The important bits are in red: ```void render(void){ D3DXMATRIX matWorld; D3DXMATRIX trans_matrix; //Our translation matrix D3DXMATRIX z_rot_matrix; static float z_rot=0; z_rot+=0.001f; //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)); //Set up the rotation matrix for the triangle D3DXMatrixRotationZ(&z_rot_matrix,z_rot); //Set up the translation matrix (move it over to the left a bit) D3DXMatrixTranslation(&trans_matrix,-1.0,0.0f,0.0f); //Combine our matrices D3DXMatrixMultiply(&matWorld,&z_rot_matrix,&trans_matrix); //Set our World Matrix g_d3d_device->SetTransform(D3DTS_WORLD,&matWorld ); //After all that setup, actually drawing the triangle is pretty easy. //We tell it what we're giving it (a Triangle List), where it should //start reading (0, the beginning), and how many triangles we're drawing(1) g_d3d_device->DrawPrimitive(D3DPT_TRIANGLELIST,0,1); //Now we go through the same steps as above, this time using our own //RotationZ function instead of the D3DX version. dhMatrixRotationZ(&z_rot_matrix,z_rot); //Move this one a bit to the right D3DXMatrixTranslation(&trans_matrix,1.0,0.0f,0.0f); D3DXMatrixMultiply(&matWorld,&z_rot_matrix,&trans_matrix); 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 ); } ```