triangleBinding.cpp

Matrix4 Md2Model::GetTrianglePos(int frameA, int frameB, float interp, int index, const Vector3& localOffset, const Vector3& localRot) {
	Vector3 tri[3];
	if(frameA == frameB) {
		// not animating
		Md2Frame_t *pFrame = &_frames[frameA];
		for(int j = 0; j < 3; ++j) {
			Md2Vertex_t *pVert = &pFrame->verts[_triangles[index].vertex[j]];

			tri[j] = Vector3((pFrame->scale[0] * pVert->v[0] + pFrame->translate[0]) * _scale,
				(pFrame->scale[1] * pVert->v[1] + pFrame->translate[1]) * _scale,
				(pFrame->scale[2] * pVert->v[2] + pFrame->translate[2]) * _scale);

			tri[j] = tri[j] * worldTranform;
			tri[j] += worldPos;
		}
	} else {
		for(int j = 0; j < 3; ++j) {
			Md2Frame_t *pFrameA = &_frames[frameA];
			Md2Frame_t *pFrameB = &_frames[frameB];
			Md2Vertex_t *pVertA = &pFrameA->verts[_triangles[index].vertex[j]];
			Md2Vertex_t *pVertB = &pFrameB->verts[_triangles[index].vertex[j]];
			// Compute final vertex position
			vec3_t vecA, vecB;

			// First, uncompress vertex positions
			vecA[0] = pFrameA->scale[0] * pVertA->v[0] + pFrameA->translate[0];
			vecA[1] = pFrameA->scale[1] * pVertA->v[1] + pFrameA->translate[1];
			vecA[2] = pFrameA->scale[2] * pVertA->v[2] + pFrameA->translate[2];

			vecB[0] = pFrameB->scale[0] * pVertB->v[0] + pFrameB->translate[0];
			vecB[1] = pFrameB->scale[1] * pVertB->v[1] + pFrameB->translate[1];
			vecB[2] = pFrameB->scale[2] * pVertB->v[2] + pFrameB->translate[2];

			// Linear interpolation and scaling
			Vector3 temp((vecA[0] + interp * (vecB[0] - vecA[0])) * _scale,
				(vecA[1] + interp * (vecB[1] - vecA[1])) * _scale,
				(vecA[2] + interp * (vecB[2] - vecA[2])) * _scale);

			temp = temp * worldTranform;
			temp += worldPos;
			tri[j] = temp;
		}
	}

	Vector3 u(tri[1] - tri[0]);
	Vector3 v(tri[2] - tri[0]);
	Vector3 normal = Vector3::cross(u.normalize(), v.normalize()).normalize();
	Vector3 tangent, bitangent;
	Vector3 triPos = (tri[0] + tri[1] + tri[2]) / 3.0f;

	// find tangent
	tangent = Vector3::cross(u, normal).normalize();
	bitangent = Vector3::cross(tangent, normal);

	return Matrix4::createFromHeadPitchRoll(localRot.x, localRot.y, localRot.z) *  Matrix4::createTranslate(localOffset.x, localOffset.y, localOffset.z) * Matrix4::createFromAxes(tangent, bitangent, normal) * Matrix4::createTranslate(triPos.x, triPos.y, triPos.z);
}