From Marco Jez, tangent space generator.
This commit is contained in:
Robert Osfield
218
src/osgUtil/TangentSpaceGenerator.cpp
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218
src/osgUtil/TangentSpaceGenerator.cpp
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#include <osgUtil/TangentSpaceGenerator>
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#include <osg/Notify>
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using namespace osgUtil;
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TangentSpaceGenerator::TangentSpaceGenerator()
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: osg::Referenced(),
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T_(new osg::Vec4Array),
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B_(new osg::Vec4Array),
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N_(new osg::Vec4Array)
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{
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}
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TangentSpaceGenerator::TangentSpaceGenerator(const TangentSpaceGenerator ©, const osg::CopyOp ©op)
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: osg::Referenced(copy),
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T_(static_cast<osg::Vec4Array *>(copyop(copy.T_.get()))),
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B_(static_cast<osg::Vec4Array *>(copyop(copy.B_.get()))),
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N_(static_cast<osg::Vec4Array *>(copyop(copy.N_.get())))
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{
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}
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void TangentSpaceGenerator::generate(osg::Geometry *geo, int normal_map_tex_unit)
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{
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const osg::Array *vx = geo->getVertexArray();
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const osg::Array *tx = geo->getTexCoordArray(normal_map_tex_unit);
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if (!vx || !tx) return;
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unsigned int vertex_count = vx->getNumElements();
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T_->assign(vertex_count, osg::Vec4());
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B_->assign(vertex_count, osg::Vec4());
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N_->assign(vertex_count, osg::Vec4());
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unsigned i; // VC6 doesn't like for-scoped variables
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for (i=0; i<geo->getNumPrimitiveSets(); ++i) {
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osg::PrimitiveSet *pset = geo->getPrimitiveSet(i);
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switch (pset->getMode()) {
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case osg::PrimitiveSet::TRIANGLES:
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for (i=0; i<pset->getNumIndices(); i+=3) {
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compute_basis_vectors(pset, vx, tx, i, i+1, i+2);
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}
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break;
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case osg::PrimitiveSet::TRIANGLE_STRIP:
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for (i=0; i<pset->getNumIndices()-2; ++i) {
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if ((i%2) == 0) {
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compute_basis_vectors(pset, vx, tx, i, i+1, i+2);
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} else {
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compute_basis_vectors(pset, vx, tx, i, i+2, i+1);
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}
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}
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break;
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case osg::PrimitiveSet::TRIANGLE_FAN:
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for (i=2; i<pset->getNumIndices(); ++i) {
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compute_basis_vectors(pset, vx, tx, 0, i-1, i);
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}
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break;
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case osg::PrimitiveSet::QUADS:
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for (i=0; i<pset->getNumIndices(); i+=4) {
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compute_basis_vectors(pset, vx, tx, i, i+1, i+2);
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compute_basis_vectors(pset, vx, tx, i+2, i+3, i);
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}
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break;
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case osg::PrimitiveSet::POINTS:
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case osg::PrimitiveSet::LINES:
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case osg::PrimitiveSet::LINE_STRIP:
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case osg::PrimitiveSet::LINE_LOOP:
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break;
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default: osg::notify(osg::WARN) << "Warning: TangentSpaceGenerator: unknown primitive mode " << pset->getMode() << "\n";
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}
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}
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// normalize basis vectors and force the normal vector to match
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// the triangle normal's direction
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for (i=0; i<vertex_count; ++i) {
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osg::Vec4 &vT = T_->at(i);
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osg::Vec4 &vB = B_->at(i);
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osg::Vec4 &vN = N_->at(i);
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osg::Vec3 txN = osg::Vec3(vT.x(), vT.y(), vT.z()) ^ osg::Vec3(vB.x(), vB.y(), vB.z());
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if (txN * osg::Vec3(vN.x(), vN.y(), vN.z()) >= 0) {
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vN = osg::Vec4(txN, 0);
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} else {
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vN = osg::Vec4(-txN, 0);
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}
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vT.normalize();
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vB.normalize();
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vN.normalize();
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}
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}
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void TangentSpaceGenerator::compute_basis_vectors(osg::PrimitiveSet *pset, const osg::Array *vx, const osg::Array *tx, int iA, int iB, int iC)
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{
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iA = pset->index(iA);
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iB = pset->index(iB);
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iC = pset->index(iC);
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osg::Vec3 P1;
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osg::Vec3 P2;
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osg::Vec3 P3;
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int i; // VC6 doesn't like for-scoped variables
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switch (vx->getType())
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{
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case osg::Array::Vec2ArrayType:
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for (i=0; i<2; ++i) {
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P1.ptr()[i] = static_cast<const osg::Vec2Array *>(vx)->at(iA).ptr()[i];
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P2.ptr()[i] = static_cast<const osg::Vec2Array *>(vx)->at(iB).ptr()[i];
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P3.ptr()[i] = static_cast<const osg::Vec2Array *>(vx)->at(iC).ptr()[i];
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}
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break;
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case osg::Array::Vec3ArrayType:
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P1 = static_cast<const osg::Vec3Array *>(vx)->at(iA);
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P2 = static_cast<const osg::Vec3Array *>(vx)->at(iB);
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P3 = static_cast<const osg::Vec3Array *>(vx)->at(iC);
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break;
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case osg::Array::Vec4ArrayType:
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for (i=0; i<3; ++i) {
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P1.ptr()[i] = static_cast<const osg::Vec4Array *>(vx)->at(iA).ptr()[i];
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P2.ptr()[i] = static_cast<const osg::Vec4Array *>(vx)->at(iB).ptr()[i];
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P3.ptr()[i] = static_cast<const osg::Vec4Array *>(vx)->at(iC).ptr()[i];
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}
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break;
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default:
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osg::notify(osg::WARN) << "Warning: TangentSpaceGenerator: vertex array must be Vec2Array, Vec3Array or Vec4Array" << std::endl;
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}
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osg::Vec2 uv1;
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osg::Vec2 uv2;
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osg::Vec2 uv3;
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switch (tx->getType())
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{
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case osg::Array::Vec2ArrayType:
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uv1 = static_cast<const osg::Vec2Array *>(tx)->at(iA);
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uv2 = static_cast<const osg::Vec2Array *>(tx)->at(iB);
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uv3 = static_cast<const osg::Vec2Array *>(tx)->at(iC);
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break;
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case osg::Array::Vec3ArrayType:
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for (i=0; i<2; ++i) {
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uv1.ptr()[i] = static_cast<const osg::Vec3Array *>(tx)->at(iA).ptr()[i];
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uv2.ptr()[i] = static_cast<const osg::Vec3Array *>(tx)->at(iB).ptr()[i];
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uv3.ptr()[i] = static_cast<const osg::Vec3Array *>(tx)->at(iC).ptr()[i];
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}
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break;
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case osg::Array::Vec4ArrayType:
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for (i=0; i<2; ++i) {
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uv1.ptr()[i] = static_cast<const osg::Vec4Array *>(tx)->at(iA).ptr()[i];
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uv2.ptr()[i] = static_cast<const osg::Vec4Array *>(tx)->at(iB).ptr()[i];
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uv3.ptr()[i] = static_cast<const osg::Vec4Array *>(tx)->at(iC).ptr()[i];
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}
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break;
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default:
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osg::notify(osg::WARN) << "Warning: TangentSpaceGenerator: texture coord array must be Vec2Array, Vec3Array or Vec4Array" << std::endl;
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}
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osg::Vec3 face_normal = (P2 - P1) ^ (P3 - P1);
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osg::Vec3 V;
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V = osg::Vec3(P2.x() - P1.x(), uv2.x() - uv1.x(), uv2.y() - uv1.y()) ^
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osg::Vec3(P3.x() - P1.x(), uv3.x() - uv1.x(), uv3.y() - uv1.y());
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if (V.x() != 0) {
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V.normalize();
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T_->at(iA).x() += -V.y() / V.x();
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B_->at(iA).x() += -V.z() / V.x();
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T_->at(iB).x() += -V.y() / V.x();
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B_->at(iB).x() += -V.z() / V.x();
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T_->at(iC).x() += -V.y() / V.x();
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B_->at(iC).x() += -V.z() / V.x();
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}
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V = osg::Vec3(P2.y() - P1.y(), uv2.x() - uv1.x(), uv2.y() - uv1.y()) ^
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osg::Vec3(P3.y() - P1.y(), uv3.x() - uv1.x(), uv3.y() - uv1.y());
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if (V.x() != 0) {
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V.normalize();
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T_->at(iA).y() += -V.y() / V.x();
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B_->at(iA).y() += -V.z() / V.x();
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T_->at(iB).y() += -V.y() / V.x();
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B_->at(iB).y() += -V.z() / V.x();
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T_->at(iC).y() += -V.y() / V.x();
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B_->at(iC).y() += -V.z() / V.x();
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}
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V = osg::Vec3(P2.z() - P1.z(), uv2.x() - uv1.x(), uv2.y() - uv1.y()) ^
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osg::Vec3(P3.z() - P1.z(), uv3.x() - uv1.x(), uv3.y() - uv1.y());
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if (V.x() != 0) {
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V.normalize();
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T_->at(iA).z() += -V.y() / V.x();
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B_->at(iA).z() += -V.z() / V.x();
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T_->at(iB).z() += -V.y() / V.x();
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B_->at(iB).z() += -V.z() / V.x();
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T_->at(iC).z() += -V.y() / V.x();
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B_->at(iC).z() += -V.z() / V.x();
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}
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N_->at(iA) += osg::Vec4(face_normal, 0);
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N_->at(iB) += osg::Vec4(face_normal, 0);
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N_->at(iC) += osg::Vec4(face_normal, 0);
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}
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