sub

Subtracts sources.

sub dest, src0, src1

Registers

dest

Destination register, holding the result of the operation.

src0

Input source register, specifying the input argument.

src1

Input source register, specifying the input argument.

To learn more about registers, see Registers.

Remarks

This instruction performs the subtraction shown in this formula.

dest = src0 - src1

Example

The following example subtracts two colors.

// shader file
vs.1.0
m4x4 oPos, v0, c0	; transform vertices by view/projection matrix
mov r0, c6		    ; load off-white
mov r1, c7		    ; load gray
sub r2, r0, r1		    ; subtract gray from off-white
mov oD0, r2		    ; output darker gray 


The resultant vertex color is a darker gray and is shown below.

// additional code is required to initialize the constant registers.
// c0 is loaded with the view and projection matrix using the m4x4 
// instruction (the m4x4 instruction also uses the c1, c2 and c3 registers).
// The last two methods set the constant color registers c6 and c7.

D3DXMATRIX mat, matView, matProj;
D3DXMatrixMultiply(&mat, &matView, &matProj);
D3DXMatrixTranspose(&mat, &mat);
// set C0 with the view and projection matrix
m_pd3dDevice->SetVertexShaderConstant(0, &mat, 4);

// set register c6
float colorOffWhite[] = {0.9f, 0.9f, 0.9f, 0.9f};
m_pd3dDevice->SetVertexShaderConstant(6, &colorOffWhite, 1);

// set register c7
float colorGray[] = {0.5f, 0.5f, 0.5f, 0.5f};
m_pd3dDevice->SetVertexShaderConstant(7, &colorGray, 1);