added ear clipping triangulation
This commit is contained in:
Richard Fabian
@@ -971,10 +971,22 @@ static void InitMaterial(material_t *material) {
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material->unknown_parameter.clear();
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}
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// code from https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html
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static int pnpoly(int nvert, float *vertx, float *verty, float testx, float testy)
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{
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int i, j, c = 0;
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for (i = 0, j = nvert-1; i < nvert; j = i++) {
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if ( ((verty[i]>testy) != (verty[j]>testy)) &&
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(testx < (vertx[j]-vertx[i]) * (testy-verty[i]) / (verty[j]-verty[i]) + vertx[i]) )
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c = !c;
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}
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return c;
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}
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static bool exportFaceGroupToShape(
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shape_t *shape, const std::vector<std::vector<vertex_index> > &faceGroup,
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const std::vector<tag_t> &tags, const int material_id,
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const std::string &name, bool triangulate) {
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const std::string &name, bool triangulate, const std::vector<real_t> &v) {
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if (faceGroup.empty()) {
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return false;
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}
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@@ -990,6 +1002,150 @@ static bool exportFaceGroupToShape(
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size_t npolys = face.size();
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if (triangulate) {
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#define ENABLE_EAR_CLIPPING 1
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#if ENABLE_EAR_CLIPPING
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// find the two axes to work in
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float min_values[3], max_values[3];
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for( size_t k = 0; k < 3; k++ ) {
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min_values[k] = (HUGE_VAL);
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max_values[k] = -(HUGE_VAL);
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}
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for(size_t f = 0; f < npolys; ++f) {
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int vi = face[f].v_idx;
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for(size_t k = 0; k < 3; k++ ) {
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float value = v[size_t(vi)*3+k];
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if( value < min_values[k] ) min_values[k] = value;
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if( value > max_values[k] ) max_values[k] = value;
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}
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}
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for(size_t k = 0; k < 3; k++ ) {
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max_values[k] -= min_values[k];
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}
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size_t axes[2] = { 1, 2 };
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if( max_values[0] > max_values[1] || max_values[0] > max_values[2] ) {
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axes[0] = 0;
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if( max_values[1] > max_values[2] )
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axes[1] = 1;
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}
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real_t area = 0;
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for(size_t k = 0; k < npolys; ++k) {
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i0 = face[(k+0)%npolys];
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i1 = face[(k+1)%npolys];
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i2 = face[(k+2)%npolys];
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size_t vi0 = size_t(i0.v_idx);
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size_t vi1 = size_t(i1.v_idx);
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size_t vi2 = size_t(i2.v_idx);
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real_t v0x = v[vi0*3+axes[0]];
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real_t v0y = v[vi0*3+axes[1]];
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real_t v1x = v[vi1*3+axes[0]];
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real_t v1y = v[vi1*3+axes[1]];
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real_t v2x = v[vi2*3+axes[0]];
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real_t v2y = v[vi2*3+axes[1]];
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real_t e0x = v1x - v0x;
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real_t e0y = v1y - v0y;
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real_t e1x = v2x - v1x;
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real_t e1y = v2y - v1y;
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area += e0x*e1y - e0y*e1x;
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}
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int maxRounds = 10; // arbitrary max loop count to protect against unexpected errors
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std::vector<vertex_index> remainingFace = face;
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size_t guess_vert = 0;
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vertex_index ind[3];
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real_t vx[3];
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real_t vy[3];
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while( remainingFace.size() > 3 && maxRounds > 0 ) {
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npolys = remainingFace.size();
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if( guess_vert >= npolys ) {
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maxRounds -= 1;
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guess_vert -= npolys;
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}
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for( size_t k = 0; k < 3; k++ ) {
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ind[k] = remainingFace[(guess_vert+k)%npolys];
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size_t vi = size_t(ind[k].v_idx);
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vx[k] = v[vi*3+axes[0]];
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vy[k] = v[vi*3+axes[1]];
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}
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real_t e0x = vx[1] - vx[0];
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real_t e0y = vy[1] - vy[0];
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real_t e1x = vx[2] - vx[1];
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real_t e1y = vy[2] - vy[1];
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real_t cross = e0x*e1y - e0y*e1x;
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// if an internal angle
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if( cross * area < 0.0f ) { guess_vert += 1; continue; }
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// check all other verts in case they are inside this triangle
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bool overlap = false;
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for( size_t otherVert = 3; otherVert < npolys; ++otherVert ) {
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size_t ovi = size_t(remainingFace[(guess_vert+otherVert)%npolys].v_idx);
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real_t tx = v[ovi*3+axes[0]];
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real_t ty = v[ovi*3+axes[1]];
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if( pnpoly( 3, vx, vy, tx, ty ) ) {
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overlap = true;
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break;
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}
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}
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if( overlap ) { guess_vert += 1; continue; }
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// this triangle is an ear
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{
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index_t idx0, idx1, idx2;
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idx0.vertex_index = ind[0].v_idx;
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idx0.normal_index = ind[0].vn_idx;
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idx0.texcoord_index = ind[0].vt_idx;
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idx1.vertex_index = ind[1].v_idx;
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idx1.normal_index = ind[1].vn_idx;
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idx1.texcoord_index = ind[1].vt_idx;
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idx2.vertex_index = ind[2].v_idx;
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idx2.normal_index = ind[2].vn_idx;
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idx2.texcoord_index = ind[2].vt_idx;
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shape->mesh.indices.push_back(idx0);
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shape->mesh.indices.push_back(idx1);
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shape->mesh.indices.push_back(idx2);
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shape->mesh.num_face_vertices.push_back(3);
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shape->mesh.material_ids.push_back(material_id);
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}
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// remove v1 from the list
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size_t removed_vert_index = (guess_vert+1)%npolys;
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while( removed_vert_index + 1 < npolys ) {
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remainingFace[removed_vert_index] = remainingFace[removed_vert_index+1];
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removed_vert_index += 1;
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}
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remainingFace.pop_back();
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}
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if( remainingFace.size() == 3 ) {
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i0 = remainingFace[0];
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i1 = remainingFace[1];
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i2 = remainingFace[2];
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{
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index_t idx0, idx1, idx2;
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idx0.vertex_index = i0.v_idx;
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idx0.normal_index = i0.vn_idx;
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idx0.texcoord_index = i0.vt_idx;
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idx1.vertex_index = i1.v_idx;
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idx1.normal_index = i1.vn_idx;
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idx1.texcoord_index = i1.vt_idx;
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idx2.vertex_index = i2.v_idx;
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idx2.normal_index = i2.vn_idx;
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idx2.texcoord_index = i2.vt_idx;
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shape->mesh.indices.push_back(idx0);
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shape->mesh.indices.push_back(idx1);
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shape->mesh.indices.push_back(idx2);
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shape->mesh.num_face_vertices.push_back(3);
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shape->mesh.material_ids.push_back(material_id);
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}
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}
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#else
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// Polygon -> triangle fan conversion
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for (size_t k = 2; k < npolys; k++) {
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i1 = i2;
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@@ -1013,6 +1169,7 @@ static bool exportFaceGroupToShape(
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shape->mesh.num_face_vertices.push_back(3);
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shape->mesh.material_ids.push_back(material_id);
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}
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#endif
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} else {
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for (size_t k = 0; k < npolys; k++) {
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index_t idx;
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@@ -1657,7 +1814,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
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// this time.
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// just clear `faceGroup` after `exportFaceGroupToShape()` call.
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exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
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triangulate);
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triangulate, v);
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faceGroup.clear();
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material = newMaterialId;
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}
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@@ -1712,7 +1869,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
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if (token[0] == 'g' && IS_SPACE((token[1]))) {
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// flush previous face group.
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bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
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triangulate);
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triangulate, v);
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(void)ret; // return value not used.
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if (shape.mesh.indices.size() > 0) {
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@@ -1749,7 +1906,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
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if (token[0] == 'o' && IS_SPACE((token[1]))) {
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// flush previous face group.
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bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
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triangulate);
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triangulate, v);
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if (ret) {
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shapes->push_back(shape);
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}
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@@ -1799,7 +1956,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
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}
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bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
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triangulate);
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triangulate, v);
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// exportFaceGroupToShape return false when `usemtl` is called in the last
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// line.
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// we also add `shape` to `shapes` when `shape.mesh` has already some
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