In The Name of God. Hi . I Want to flip my object . i have used this code for vertex shader: v2p vertexProgram (float4 normal:NORMAL,float2 tex:TEXCOORD0,float4 pos:POSITION) { v2p output = (v2p)0; ///* Commented **// //normal = mul(normal,WorldInverseTranspose); ///* Commented **// output.normal = -normal; output.pos = mul(pos,wvp); output.tex = tex; return output; } But there is nothing as result , no changes will affect . I want also rotate my normals by this matrix with mul function : float4x4 rot = { {1.0 , 0.0 , 0.0 , 0.0}, {0.0 , 0.707 , -0.707 , 0.0}, {0.0 , 0.707 , 0.707 , 0.0}, {0.0 , 0.0 , 0.0 , 1.0}}; please help . thanks in advance ....

output.pos = mul(-pos,wvp);

mul( input.normal, rot );

when i use mul(-pos , wvp) my screen turns to black .