/**
*
* @param P0
* @param P1
* @param P2
* @param P
* @param n
* @return
*
* @see http://www.cs.cornell.edu/courses/cs465/2003fa/homeworks/raytri.pdf
*/
bool isInsideTheTriangle(Vector4& P0, Vector4& P1, Vector4& P2, Vector4& P, Vector4& n){
//Vector from one vertex to other vertex.
auto_ptr<Vector4> Edge01(P0.Subtract(P1, P0));
auto_ptr<Vector4> Edge12(P1.Subtract(P2, P1));
auto_ptr<Vector4> Edge20(P2.Subtract(P0, P2));
//Vector from one vertex to the point of intersection.
auto_ptr<Vector4> X0(P.Subtract(P,P0));
auto_ptr<Vector4> X1(P.Subtract(P,P1));
auto_ptr<Vector4> X2(P.Subtract(P,P2));
//Cross Products of the above two.
auto_ptr<Vector4> Product1(Edge01->CrossProduct(*Edge01, *X0));
auto_ptr<Vector4> Product2(Edge12->CrossProduct(*Edge12, *X1));
auto_ptr<Vector4> Product3(Edge20->CrossProduct(*Edge20, *X2));
//Dot product with normals.
double d1 = Product1->DotProduct(*Product1, n);
double d2 = Product2->DotProduct(*Product2, n);
double d3 = Product3->DotProduct(*Product3, n);
if((d1>=0 and d2>=0 and d3>=0) or (d1<=0 and d2<=0 and d3<=0)){
return true;
}else{
return false;
}
}
Vector4* findReflectedRayDirection(Vector4 &N, Vector4& L){
Vector4* R;
Vector4* Rtemp = new Vector4();
Rtemp->SetVector4(0,0,0,1);
Rtemp->GetCopyOf(N);
double N_dot_L = N.DotProduct(N,L);
Rtemp->Elongate(2*N_dot_L);
R = Rtemp->Subtract(*Rtemp,L);
delete Rtemp;
return R;
}
void Mesh::CalculateFlatLightingDirectional(const LightDirectional &light, int numLights, const Vector4& cameraPos, const Matrix4& view)
{
Maths::Vector4 total, temp;
Maths::Vector4 reflect;
Maths::Vector4 v = cameraPos;
Maths::Vector4 l( light.Position.X, light.Position.Y, light.Position.Z, 1.0f );
Maths::Vector4 n( 0, 0, 0 );
Maths::Vector4 t, halfWay;
BYTE r, g, b;
float spec = 0;
float diff = 0;
float ave = 0;
m_noLight = false;
//workout the "halfway" vector for specularity
ave = v.Length();
//halfWay = ( v + l ) / ave;
//halfWay.Normalize();
//normalize the light position
l.Normalize();
for ( int i = 0; i < m_numPolys; ++i )
{
if ( !m_polys[i].IsCulled )
{
//reset the colout to black
total.X = 0; //Red
total.Y = 0; //green
total.Z = 0; //blue
for ( int j = 0; j < numLights; ++j )
{
//store intensity to corresponding variables
//modulate intensity with coresponding reflectance co-efficient values
temp.X = light.Colour.GetR() * light.Intensity.X;
temp.Y = light.Colour.GetG() * light.Intensity.Y;
temp.Z = light.Colour.GetB() * light.Intensity.Z;
//reflect = ( 2 * ( m_polys[i]._normal.DotProduct( light._position ) ) * ( m_polys[i]._normal - light );
n.SetValues( m_polys[i].Normal.X, m_polys[i].Normal.Y, m_polys[i].Normal.Z, 1.0f );
n.Normalize();
//attentuate the rgb values with lambertian attenuation
diff = max( 0.0f, l.DotProduct( n ) );
//calculate specular coponent
Vector4 toEye;
Matrix4::Transform( view, m_transformed[ m_polys[i].Indices[0] ].Position, toEye );
toEye.Normalize();
float r = max( 0, m_transformed[ m_polys[i].Indices[0] ].Normal.DotProduct( l ) );
Vector4 reflect = m_transformed[ m_polys[i].Indices[0] ].Normal;
reflect.Multiply( 2 * r );
reflect.Subtract( l );
//Vector4 toEye = m_transformed[ m_polys[i]._indices[0] ]._position - viewer;
//Vector4 reflect = ( n - l ) * ( 2 * ( n.DotProduct( l ) ) );
toEye.Normalize();
reflect.Normalize();
float specPower = 1.0f;
float spec = 0; //max( 0, pow( max( 0.0f, reflect.DotProduct( toEye ) ), specPower ) ) * m_specular;
if ( diff <= 0.0f )
spec = 0.0f;
temp.X = temp.X * ( (diff + spec) * m_kd_red );
temp.Y = temp.Y * ( (diff + spec) * m_kd_green );
temp.Z = temp.Z * ( (diff + spec) * m_kd_blue );
total = total + temp;
}
//clamp the values
if (total.X > 255) total.X = 255;
if (total.Y > 255) total.Y = 255;
if (total.Z > 255) total.Z = 255;
if (total.X < 0) total.X = 0;
if (total.Y < 0) total.Y = 0;
if (total.Z < 0) total.Z = 0;
r = (BYTE)total.X;
g = (BYTE)total.Y;
b = (BYTE)total.Z;
m_polys[i].Colour = Gdiplus::Color::MakeARGB(255, r, g, b);
}
}
}
