inline void InsertRecord (const String& name, uint elements)
{
Record& r = g_uniforms.Expand();
r.name = name;
r.elements = elements;
}
void Mesh::_CalculateNormalsAndTangents()
{
if (mT.IsValid() || mV.IsEmpty()) return;
// Don't bother with points or lines
if (mPrimitive == IGraphics::Primitive::Point ||
mPrimitive == IGraphics::Primitive::Line ||
mPrimitive == IGraphics::Primitive::LineStrip) return;
// Allocate a temporary buffer to store binormals
Array<Vector3f> binormals (mV.GetSize());
// Remember whether we already have normals to work with
bool calculateNormals = (mV.GetSize() != mN.GetSize());
// We can only calculate tangents if the texture coordinates are available
bool calculateTangents = (mV.GetSize() == mTc0.GetSize());
// If we should calculate normals, clear the existing normal array
if (calculateNormals)
{
mN.Clear();
mN.ExpandTo(mV.GetSize());
}
// Expand the tangent array
if (calculateTangents) mT.ExpandTo(mV.GetSize());
// The number of indices
uint size = mIndices.IsValid() ? mIndices.GetSize() : GetNumberOfVertices();
// Triangles
if (size > 2)
{
bool even = true;
uint i0, i1, i2;
for (uint i = 0; i + 2 < size; )
{
i0 = i;
i1 = i+1;
i2 = i+2;
if (mIndices.IsValid())
{
i0 = mIndices[i0];
i1 = mIndices[i1];
i2 = mIndices[i2];
}
ASSERT(i0 < mV.GetSize(), "Index out of bounds!");
ASSERT(i1 < mV.GetSize(), "Index out of bounds!");
ASSERT(i2 < mV.GetSize(), "Index out of bounds!");
const Vector3f& v0 ( mV[i0] );
const Vector3f& v1 ( mV[i1] );
const Vector3f& v2 ( mV[i2] );
Vector3f v10 (v1 - v0);
Vector3f v20 (v2 - v0);
if (calculateNormals)
{
Vector3f normal (Cross(v10, v20));
mN[i0] += normal;
mN[i1] += normal;
mN[i2] += normal;
}
if (calculateTangents)
{
const Vector2f& t0 ( mTc0[i0] );
const Vector2f& t1 ( mTc0[i1] );
const Vector2f& t2 ( mTc0[i2] );
Vector2f t10 (t1 - t0);
Vector2f t20 (t2 - t0);
float denominator = t10.x * t20.y - t20.x * t10.y;
if ( Float::IsNotZero(denominator) )
{
float scale = 1.0f / denominator;
Vector3f tangent ((v10.x * t20.y - v20.x * t10.y) * scale,
(v10.y * t20.y - v20.y * t10.y) * scale,
(v10.z * t20.y - v20.z * t10.y) * scale);
Vector3f binormal((v20.x * t10.x - v10.x * t20.x) * scale,
(v20.y * t10.x - v10.y * t20.x) * scale,
(v20.z * t10.x - v10.z * t20.x) * scale);
mT[i0] += tangent;
mT[i1] += tangent;
mT[i2] += tangent;
binormals[i0] += binormal;
binormals[i1] += binormal;
binormals[i2] += binormal;
}
}
if (mPrimitive == IGraphics::Primitive::Triangle)
{
i += 3;
}
else if (mPrimitive == IGraphics::Primitive::Quad)
{
if (even) ++i;
else i += 3;
even = !even;
}
else ++i;
}
// If we're calculating normals we need to match all normals with identical vertices
if (calculateNormals)
{
Array<uint> matches;
for (uint i = 0; i < mV.GetSize(); ++i)
{
matches.Clear();
matches.Expand() = i;
Vector3f N = mN[i];
const Vector3f& V (mV[i]);
for (uint b = 0; b < mV.GetSize(); ++b)
{
if (i != b && V == mV[b])
{
matches.Expand() = b;
N += mN[b];
}
}
N.Normalize();
for (uint b = 0; b < matches.GetSize(); ++b)
{
mN[ matches[b] ] = N;
}
}
}
}
if (calculateTangents)
{
// Normalize all tangents
for (uint i = 0; i < mV.GetSize(); ++i)
{
Vector3f& T (mT[i]);
Vector3f& B (binormals[i]);
Vector3f& N (mN[i]);
// In order to avoid visible seams, the tangent should be 90 degrees to the normal
// Note to self: Gram-Schmidt formula for the cross product below: T = T - N * Dot(N, T);
T = Cross(B, N);
T.Normalize();
// Flip the tangent if the handedness is incorrect
if (Dot(Cross(T, B), N) < 0.0f) T.Flip();
}
}
}
