Add skin weight support(vw tag. tinyobjloader extension)

syoyo · syoyo · commit 19c3ec9e2efb · 2020-03-09T14:39:48.000+09:00
diff --git a/examples/skin_weight/Makefile b/examples/skin_weight/Makefile
@@ -0,0 +1,2 @@
+all:
+	clang++ -std=c++11 -o skin_weight -I../../ -g main.cc
diff --git a/examples/skin_weight/README.md b/examples/skin_weight/README.md
@@ -0,0 +1,7 @@
+This example printf skin weight of vertex(`vw`). TinyObjLoader extension.
+
+## Run example
+
+```
+$ ./skin_weight ../../models/skin-weight.obj
+```
diff --git a/examples/skin_weight/main.cc b/examples/skin_weight/main.cc
@@ -0,0 +1,103 @@
+//
+// g++ -g -std=c++11 main.cc
+//
+#define TINYOBJLOADER_IMPLEMENTATION
+#include "tiny_obj_loader.h"
+
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <sstream>
+
+#include <unordered_map> // C++11
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#if __has_warning("-Wzero-as-null-pointer-constant")
+#pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
+#endif
+#endif
+
+static void ConstructVertexWeight(
+  const std::vector<tinyobj::real_t> &vertices,
+  const std::vector<tinyobj::skin_weight_t> &skin_weights,
+  std::vector<tinyobj::skin_weight_t> *vertex_skin_weights)
+{
+  size_t num_vertices = vertices.size() / 3;
+
+  vertex_skin_weights->resize(num_vertices);
+
+  for (size_t i = 0; i < skin_weights.size(); i++) {
+    const tinyobj::skin_weight_t &skin = skin_weights[i];
+
+    assert(skin.vertex_id >= 0);
+    assert(skin.vertex_id < num_vertices);
+
+    (*vertex_skin_weights)[skin.vertex_id] = skin;
+  }
+
+  // now you can lookup i'th vertex skin weight by `vertex_skin_weights[i]`
+
+
+}
+
+static bool TestLoadObj(const char* filename, const char* basepath = nullptr,
+                        bool triangulate = true) {
+  std::cout << "Loading " << filename << std::endl;
+
+  tinyobj::attrib_t attrib;
+  std::vector<tinyobj::shape_t> shapes;
+  std::vector<tinyobj::material_t> materials;
+
+  std::string warn;
+  std::string err;
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &warn, &err, filename,
+                              basepath, triangulate);
+  if (!warn.empty()) {
+    std::cout << "WARN: " << warn << std::endl;
+  }
+
+  if (!err.empty()) {
+    std::cerr << "ERR: " << err << std::endl;
+  }
+
+  if (!ret) {
+    printf("Failed to load/parse .obj.\n");
+    return false;
+  }
+
+  std::vector<tinyobj::skin_weight_t> vertex_skin_weights;
+
+  ConstructVertexWeight(
+    attrib.vertices,
+    attrib.skin_weights,
+    &vertex_skin_weights);
+
+  for (size_t v = 0; v < vertex_skin_weights.size(); v++) {
+    std::cout << "vertex[" << v << "] num_weights = " << vertex_skin_weights[v].weightValues.size() << "\n";
+    for (size_t w = 0; w < vertex_skin_weights[v].weightValues.size(); w++) {
+      std::cout << "  w[" << w << "] joint = " << vertex_skin_weights[v].weightValues[w].joint_id
+                << ", weight = " << vertex_skin_weights[v].weightValues[w].weight << "\n";
+    }
+  }
+
+  return true;
+}
+
+
+int main(int argc, char** argv) {
+  if (argc < 2) {
+    std::cerr << "Need input.obj\n";
+    return EXIT_FAILURE;
+  }
+
+  const char* basepath = nullptr;
+  if (argc > 2) {
+   basepath = argv[2];
+  }
+  assert(true == TestLoadObj(argv[1], basepath));
+
+  return 0;
+}
diff --git a/models/skin-weight.obj b/models/skin-weight.obj
@@ -0,0 +1,43 @@
+mtllib cube.mtl
+
+v 0.000000 2.000000 2.000000
+v 0.000000 0.000000 2.000000
+v 2.000000 0.000000 2.000000
+v 2.000000 2.000000 2.000000
+v 0.000000 2.000000 0.000000
+v 0.000000 0.000000 0.000000
+v 2.000000 0.000000 0.000000
+v 2.000000 2.000000 0.000000
+# 8 vertices
+
+vw 0 0 1.0
+vw 1 0 0.5 1 0.5
+vw 2 1 1.0
+vw 3 2 1.0
+vw 4 3 1.0
+vw 5 0 0.25 1 0.25 2 0.25 3 0.25
+# No weight for 6th vertex
+# vw 6 0 1.0
+vw 7 0 1.0
+# max 4 joints
+
+g front cube
+usemtl white
+f 1 2 3 4
+# two white spaces between 'back' and 'cube'
+g back  cube
+# expects white material
+f 8 7 6 5
+g right cube
+usemtl red
+f 4 3 7 8
+g top cube
+usemtl white
+f 5 1 4 8
+g left cube
+usemtl green
+f 5 6 2 1
+g bottom cube
+usemtl white
+f 2 6 7 3
+# 6 elements
diff --git a/tiny_obj_loader.h b/tiny_obj_loader.h
@@ -27,6 +27,7 @@ THE SOFTWARE.
 //                 * Support line primitive.
 //                 * Support points primitive.
 //                 * Support multiple search path for .mtl(v1 API).
+//                 * Support vertex weight `vw`(as an tinyobj extension)
 // version 1.4.0 : Modifed ParseTextureNameAndOption API
 // version 1.3.1 : Make ParseTextureNameAndOption API public
 // version 1.3.0 : Separate warning and error message(breaking API of LoadObj)
@@ -162,8 +163,9 @@ struct texture_option_t {
   real_t origin_offset[3];  // -o u [v [w]] (default 0 0 0)
   real_t scale[3];          // -s u [v [w]] (default 1 1 1)
   real_t turbulence[3];     // -t u [v [w]] (default 0 0 0)
-  int   texture_resolution; // -texres resolution (No default value in the spec. We'll use -1)
-  bool clamp;    // -clamp (default false)
+  int texture_resolution;   // -texres resolution (No default value in the spec.
+                            // We'll use -1)
+  bool clamp;               // -clamp (default false)
   char imfchan;  // -imfchan (the default for bump is 'l' and for decal is 'm')
   bool blendu;   // -blendu (default on)
   bool blendv;   // -blendv (default on)
@@ -316,7 +318,6 @@ struct material_t {
   }
 
 #endif
-
 };
 
 struct tag_t {
@@ -327,6 +328,18 @@ struct tag_t {
   std::vector<std::string> stringValues;
 };
 
+struct joint_and_weight_t {
+  int joint_id;
+  real_t weight;
+};
+
+struct skin_weight_t {
+  int vertex_id;  // Corresponding vertex index in `attrib_t::vertices`.
+                  // Compared to `index_t`, this index must be positive and
+                  // start with 0(does not allow relative indexing)
+  std::vector<joint_and_weight_t> weightValues;
+};
+
 // Index struct to support different indices for vtx/normal/texcoord.
 // -1 means not used.
 struct index_t {
@@ -383,6 +396,16 @@ struct attrib_t {
   std::vector<real_t> texcoord_ws;  // 'vt'(w)
   std::vector<real_t> colors;       // extension: vertex colors
 
+  //
+  // TinyObj extension.
+  //
+
+  // NOTE(syoyo): array index is based on the appearance order.
+  // To get a corresponding skin weight for a specific vertex id `vid`,
+  // Need to reconstruct a look up table: `skin_weight_t::vertex_id` == `vid`
+  // (e.g. using std::map, std::unordered_map)
+  std::vector<skin_weight_t> skin_weights;
+
   attrib_t() {}
 
   //
@@ -625,11 +648,10 @@ bool ParseTextureNameAndOption(std::string *texname, texture_option_t *texopt,
 #include <cstddef>
 #include <cstdlib>
 #include <cstring>
-#include <limits>
-#include <utility>
-
 #include <fstream>
+#include <limits>
 #include <sstream>
+#include <utility>
 
 namespace tinyobj {
 
@@ -1917,8 +1939,7 @@ void LoadMtl(std::map<std::string, int> *material_map,
 
       // Set a decent diffuse default value if a diffuse texture is specified
       // without a matching Kd value.
-      if (!has_kd)
-      {
+      if (!has_kd) {
         material.diffuse[0] = static_cast<real_t>(0.6);
         material.diffuse[1] = static_cast<real_t>(0.6);
         material.diffuse[2] = static_cast<real_t>(0.6);
@@ -2181,6 +2202,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
   std::vector<real_t> vn;
   std::vector<real_t> vt;
   std::vector<real_t> vc;
+  std::vector<skin_weight_t> vw;
   std::vector<tag_t> tags;
   PrimGroup prim_group;
   std::string name;
@@ -2274,6 +2296,53 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
       continue;
     }
 
+    // skin weight. tinyobj extension
+    if (token[0] == 'v' && token[1] == 'w' && IS_SPACE((token[2]))) {
+      token += 3;
+
+      // vw <vid> <joint_0> <weight_0> <joint_1> <weight_1> ...
+      // example:
+      // vw 0 0 0.25 1 0.25 2 0.5
+
+      // TODO(syoyo): Add syntax check
+      int vid = 0;
+      vid = parseInt(&token);
+
+      skin_weight_t sw;
+
+      sw.vertex_id = vid;
+
+      while (!IS_NEW_LINE(token[0])) {
+        real_t j, w;
+        // joint_id should not be negative, weight may be negative
+        // TODO(syoyo): # of elements check
+        parseReal2(&j, &w, &token, -1.0);
+
+        if (j < 0.0) {
+          if (err) {
+            std::stringstream ss;
+            ss << "Failed parse `vw' line. joint_id is negative. "
+                  "line "
+               << line_num << ".)\n";
+            (*err) += ss.str();
+          }
+          return false;
+        }
+
+        joint_and_weight_t jw;
+
+        jw.joint_id = int(j);
+        jw.weight = w;
+
+        sw.weightValues.push_back(jw);
+
+        size_t n = strspn(token, " \t\r");
+        token += n;
+      }
+
+      vw.push_back(sw);
+    }
+
     // line
     if (token[0] == 'l' && IS_SPACE((token[1]))) {
       token += 2;
@@ -2675,6 +2744,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
   attrib->texcoords.swap(vt);
   attrib->texcoord_ws.swap(vt);
   attrib->colors.swap(vc);
+  attrib->skin_weights.swap(vw);
 
   return true;
 }

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+all:`
	`2`	`+ clang++ -std=c++11 -o skin_weight -I../../ -g main.cc`