private void GenerateTangentsTriangle4f(IVertexArray positionArray, IVertexArray normalArray, IVertexArray texArray, IVertexArray tanArray, IVertexArray bitanArray)
{
uint count = (ElementCount != 0 ? ElementCount : _VertexArrayObject.ArrayLength) / 3;
for (uint i = 0, v = ElementOffset; i < count; i++, v += 3)
{
Vertex3f v0 = (Vertex3f)positionArray.GetElement <Vertex4f>(v);
Vertex3f v1 = (Vertex3f)positionArray.GetElement <Vertex4f>(v + 1);
Vertex3f v2 = (Vertex3f)positionArray.GetElement <Vertex4f>(v + 2);
Vertex2f t0 = texArray.GetElement <Vertex2f>(v);
Vertex2f t1 = texArray.GetElement <Vertex2f>(v + 1);
Vertex2f t2 = texArray.GetElement <Vertex2f>(v + 2);
Vertex3f dv1 = v1 - v0, dv2 = v2 - v0;
Vertex2f dt1 = t1 - t0, dt2 = t2 - t0;
float w = 1.0f / (dt1.x * dt2.y - dt1.y * dt2.x);
Vertex3f tgVector, btVector;
if (Single.IsInfinity(w) == false)
{
tgVector = (dv1 * dt2.y - dv2 * dt1.y) * w;
tgVector.Normalize();
btVector = (dv2 * dt1.x - dv1 * dt2.x) * w;
btVector.Normalize();
Vertex3f n = normalArray.GetElement <Vertex3f>(v).Normalized;
n.Normalize();
if (((n ^ tgVector) * btVector) < 0.0f)
{
tgVector = tgVector * -1.0f;
}
}
else
{
// Degenerate triangles does not contribute
tgVector = btVector = Vertex3f.Zero;
}
tanArray.SetElement <Vertex3f>(tgVector, v);
tanArray.SetElement <Vertex3f>(tgVector, v + 1);
tanArray.SetElement <Vertex3f>(tgVector, v + 2);
bitanArray.SetElement <Vertex3f>(btVector, v);
bitanArray.SetElement <Vertex3f>(btVector, v + 1);
bitanArray.SetElement <Vertex3f>(btVector, v + 2);
}
}
private void GenerateNormalsTriangle3f(IVertexArray positionArray, IVertexArray normalArray)
{
uint count = (ElementCount != 0 ? ElementCount : _VertexArrayObject.ArrayLength) / 3;
for (uint i = 0, v = ElementOffset; i < count; i++)
{
Vertex3f v0 = positionArray.GetElement <Vertex3f>(v++);
Vertex3f v1 = positionArray.GetElement <Vertex3f>(v++);
Vertex3f v2 = positionArray.GetElement <Vertex3f>(v++);
Vertex3f n = ((v2 - v0) ^ (v1 - v0)).Normalized;
normalArray.SetElement <Vertex3f>(n, v - 2);
normalArray.SetElement <Vertex3f>(n, v - 1);
normalArray.SetElement <Vertex3f>(n, v - 0);
}
}
private void GenerateTexCoordsTriangle3f(IVertexArray positionArray, IVertexArray texArray, VertexArrayTexGenDelegate genTexCoordCallback)
{
for (uint i = 0, v = ElementOffset; i < ArrayIndices.ItemCount; i++, v++)
{
uint vIndex = ArrayIndices.GetIndex(v);
Vertex3f v0 = positionArray.GetElement <Vertex3f>(vIndex);
texArray.SetElement <Vertex2f>(genTexCoordCallback(v0), vIndex);
}
}
private void GenerateTangentsTriangleStrip3f(IVertexArray positionArray, IVertexArray normalArray, IVertexArray texArray, IVertexArray tanArray, IVertexArray bitanArray)
{
uint count = ElementCount != 0 ? ElementCount : ArrayIndices.ItemCount;
uint i0, i1, i2;
Vertex3f v0, v1, v2;
Vertex2f t0, t1, t2;
i0 = ArrayIndices.GetIndex(ElementOffset);
i1 = ArrayIndices.GetIndex(ElementOffset + 1);
v0 = positionArray.GetElement <Vertex3f>(i0);
v1 = positionArray.GetElement <Vertex3f>(i1);
t0 = texArray.GetElement <Vertex2f>(i0);
t1 = texArray.GetElement <Vertex2f>(i1);
for (uint i = 0, v = ElementOffset + 2; i < count - 2; i++, v++)
{
// Next triangle
i2 = ArrayIndices.GetIndex(v);
v2 = positionArray.GetElement <Vertex3f>(i2);
t2 = texArray.GetElement <Vertex2f>(i2);
// Compute tangent & bitangent
Vertex3f dv1 = v1 - v0, dv2 = v2 - v0;
Vertex2f dt1 = t1 - t0, dt2 = t2 - t0;
float w = 1.0f / (dt1.x * dt2.y - dt1.y * dt2.x);
Vertex3f tgVector, btVector;
if (Single.IsInfinity(w) == false)
{
tgVector = (dv1 * dt2.y - dv2 * dt1.y) * w;
tgVector.Normalize();
btVector = (dv2 * dt1.x - dv1 * dt2.x) * w;
btVector.Normalize();
//Vertex3f n = normalArray.GetElement<Vertex3f>(i2);
//n.Normalize();
//if (((n ^ tgVector) * btVector) < 0.0f)
// tgVector = tgVector * -1.0f;
}
else
{
// Degenerate triangles does not contribute
tgVector = btVector = Vertex3f.Zero;
}
// Store (accumulate adjacent triangles)
Vertex3f tg0 = tanArray.GetElement <Vertex3f>(i0) + tgVector;
Vertex3f tg1 = tanArray.GetElement <Vertex3f>(i1) + tgVector;
Vertex3f tg2 = tanArray.GetElement <Vertex3f>(i2) + tgVector;
tanArray.SetElement <Vertex3f>(tg0, i0);
tanArray.SetElement <Vertex3f>(tg1, i1);
tanArray.SetElement <Vertex3f>(tg2, i2);
Vertex3f bt0 = bitanArray.GetElement <Vertex3f>(i0) + btVector;
Vertex3f bt1 = bitanArray.GetElement <Vertex3f>(i1) + btVector;
Vertex3f bt2 = bitanArray.GetElement <Vertex3f>(i2) + btVector;
bitanArray.SetElement <Vertex3f>(bt0, i0);
bitanArray.SetElement <Vertex3f>(bt1, i1);
bitanArray.SetElement <Vertex3f>(bt2, i2);
// Prepare for next triangle
i0 = i1;
i1 = i2;
}
}
