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 out 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 );
}
