Hey all,
I'm currently working on a 3D tank game and I have a serious problem with the normals.
I'm trying to achieve smooth shading (I think that's the way this is called) by summing up all the normals of the faces of some vertex and then avaraging them.
Firstly, It didnt work well on the ground, there arent many changes (when changing the position of a light source) but when the light source is below a certrain point(Y axis), that place (the place above it) is blacked out.
so It looks like it got some affect on the ground, and i'm not sure what should I do.
here are two screen shots the red cross is the place of the light source, and by looking at the tank you can see that this is wrong:
http://img89.imageshack.us/img89/4773/normals2nz1.jpg
http://img359.imageshack.us/img359/8967/normals1kn9.jpg
before explaining what exacly I'm doing this is how i calculate each normal:
void VectorOffset (point *pIn, point *pOffset, point *pOut)
{
pOut->x = pIn->x - pOffset->x;
pOut->y = pIn->y - pOffset->y;
pOut->z = pIn->z - pOffset->z;
}
// Compute the cross product a X b into pOut
void VectorGetNormal (point *a, point *b, point *pOut)
{
pOut->x = a->y * b->z - a->z * b->y;
pOut->y = a->z * b->x - a->x * b->z;
pOut->z = a->x * b->y - a->y * b->x;
}
// Compute p1,p2,p3 face normal into pOut
bool ComputeFaceNormal (point *p1, point *p2, point *p3, point *pOut)
{
// Uses p2 as a new origin for p1,p3
point a;
VectorOffset(p3, p2, &a);
point b;
VectorOffset(p1, p2, &b);
// Compute the cross product a X b to get the face normal
point pn;
VectorGetNormal(&a, &b, &pn);
pOut->x = pn.x;
pOut->y = pn.y;
pOut->z = pn.z;
return true;
}
What I'm doing is this:
first I calculate all the normals for a certain vertex and I save it with a certain class i've made.
After all faces are loaded, i'm chaning all the normals so they'll suit up.
(NFV is an object of that class)
Numosh is the place of that Vertex's normal
(assuming there are 3 vertices, if i want the normal for the vertex in the place 1 Numosh=1)
for (vector <Mesh>::iterator JHJ=Meshes.begin();JHJ!=Meshes.end();JHJ++)
{
NumTria=0;
for (vector <Triangle>::iterator Tria = (*JHJ).Triangles.begin();Tria!=(*JHJ).Triangles.end();Tria++)
{
for (int i=0;i<3;i++)
{
int Numosh = int((*Tria).Normal.x);
point OldVector;
OldVector.x = float(NFV[Numosh].SumOfAllNormals.x/float(NFV[Numosh].numOfNormals));
OldVector.y = float(NFV[Numosh].SumOfAllNormals.y/float(NFV[Numosh].numOfNormals));
OldVector.z = float(NFV[Numosh].SumOfAllNormals.z/float(NFV[Numosh].numOfNormals));
point NewN, NewN2;
NewN.x=OldVector.x;
NewN.y=OldVector.y;
NewN.z=OldVector.z;
Meshes[NumMush].Triangles[NumTria].Normal.x=NewN.x;
Meshes[NumMush].Triangles[NumTria].Normal.y=NewN.y;
Meshes[NumMush].Triangles[NumTria].Normal.z=NewN.z;
}
NumTria++;
}
NumMush++;
}
Any idea why is this happening this way?
Thanks in advance
[Edited by - Yhonatan on July 22, 2008 5:00:28 PM]
