Add colorspace extension to texture options. Fixes #184

models/colorspace-issue-184.mtl

@@ -0,0 +1,9 @@
+newmtl default
+Ka 0 0 0
+Kd 0 0 0
+Ks 0 0 0
+Kt 0.1 0.2 0.3
+map_Kd -colorspace sRGB -o 0.1 diffuse.jpg
+map_Ks -s 0.1 0.2 specular.jpg
+map_bump -colorspace linear -bm 3 bumpmap.jpg
+

models/colorspace-issue-184.obj

@@ -0,0 +1,7 @@
+mtllib colorspace-issue-184.mtl
+o Test
+v 1.864151 -1.219172 -5.532511
+v 0.575869 -0.666304 5.896140
+v 0.940448 1.000000 -1.971128
+usemtl default
+f 1 2 3

tests/tester.cc

@@ -825,6 +825,25 @@ TEST_CASE("multiple-group-names", "[group]") {
   REQUIRE(0 == shapes[1].name.compare("back cube")); // multiple whitespaces are aggregated as single white space.
 }
 
+TEST_CASE("colorspace", "[Issue184]") {
+  tinyobj::attrib_t attrib;
+  std::vector<tinyobj::shape_t> shapes;
+  std::vector<tinyobj::material_t> materials;
+
+  std::string err;
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, "../models/colorspace-issue-184.obj", gMtlBasePath);
+
+  if (!err.empty()) {
+    std::cerr << err << std::endl;
+  }
+  REQUIRE(true == ret);
+  REQUIRE(1 == shapes.size());
+  REQUIRE(1 == materials.size());
+  REQUIRE(0 == materials[0].diffuse_texopt.colorspace.compare("sRGB"));
+  REQUIRE(0 == materials[0].specular_texopt.colorspace.size());
+  REQUIRE(0 == materials[0].bump_texopt.colorspace.compare("linear"));
+}
+
 // Fuzzer test.
 // Just check if it does not crash.
 // Disable by default since Windows filesystem can't create filename of afl testdata

tiny_obj_loader.h

@@ -23,6 +23,7 @@ THE SOFTWARE.
 */
 
 //
+// version 1.2.3 : Added color space extension('-colorspace') to tex opts.
 // version 1.2.2 : Parse multiple group names.
 // version 1.2.1 : Added initial support for line('l') primitive(PR #178)
 // version 1.2.0 : Hardened implementation(#175)
@@ -113,6 +114,11 @@ namespace tinyobj {
 //         cube_front  | cube_back   |      # side of the cube is specified
 //         separately
 //         cube_left   | cube_right
+//
+// TinyObjLoader extension.
+//
+//   -colorspace SPACE                      # Color space of the texture. e.g.  'sRGB` or 'linear' 
+// 
 
 #ifdef TINYOBJLOADER_USE_DOUBLE
 //#pragma message "using double"
@@ -147,6 +153,9 @@ typedef struct {
   bool blendu;   // -blendu (default on)
   bool blendv;   // -blendv (default on)
   real_t bump_multiplier;  // -bm (for bump maps only, default 1.0)
+  
+  // extension
+  std::string colorspace;   // Explicitly specify color space of stored value. Usually `sRGB` or `linear` (default empty).
 } texture_option_t;
 
 typedef struct {
@@ -950,6 +959,9 @@ static bool ParseTextureNameAndOption(std::string *texname,
     } else if ((0 == strncmp(token, "-mm", 3)) && IS_SPACE((token[3]))) {
       token += 4;
       parseReal2(&(texopt->brightness), &(texopt->contrast), &token, 0.0, 1.0);
+    } else if ((0 == strncmp(token, "-colorspace", 11)) && IS_SPACE((token[11]))) {
+      token += 12;
+      texopt->colorspace = parseString(&token);
     } else {
       // Assume texture filename
 #if 0