More spec-compliant rendering of albedo and metal-roughness.

4 files changed, 71 insertions, 33 deletions

diff --git a/gfx/shaders/cook_torrance.frag b/gfx/shaders/cook_torrance.frag
index 18d9d18..fcedef6 100644
--- a/gfx/shaders/cook_torrance.frag
+++ b/gfx/shaders/cook_torrance.frag
@@ -5,8 +5,12 @@ uniform float MetallicFactor;
 uniform float RoughnessFactor;
 uniform vec3  EmissiveFactor;
 
+#ifdef HAS_ALBEDO_MAP
 uniform sampler2D BaseColorTexture;
+#endif
+#ifdef HAS_METALLIC_ROUGHNESS_MAP
 uniform sampler2D MetallicRoughnessTexture;
+#endif
 #ifdef HAS_EMISSIVE_MAP
 uniform sampler2D EmissiveTexture;
 #endif
@@ -161,10 +165,22 @@ void main()
   //float HdotV = clamp(dot(H,V), 0.0, 1.0);  // Clamp to prevent black spots.
 
   // TODO: BaseColorFactor and BaseColorTexture are vec4/rgba quantities
-  // respectively. Handle the alpha channel later.
+  // respectively. Handle the alpha channel.
   // TODO: Other factors.
+#ifdef HAS_ALBEDO_MAP
   vec3 albedo = vec3(BaseColorFactor) * texture(BaseColorTexture, Texcoord).rgb;
-  vec3 metal_roughness = texture(MetallicRoughnessTexture, Texcoord).rgb;
+#else
+  vec3 albedo = vec3(BaseColorFactor);
+#endif
+#ifdef HAS_METALLIC_ROUGHNESS_MAP
+  // Spec: "Its green channel contains roughness values and its blue channel
+  // contains metalness values."
+  vec2 metal_roughness
+    = vec2(MetallicFactor, RoughnessFactor)
+    * texture(MetallicRoughnessTexture, Texcoord).bg;
+#else
+  vec2 metal_roughness = vec2(MetallicFactor, RoughnessFactor);
+#endif
 #ifdef HAS_EMISSIVE_MAP
   vec3 emissive = texture(EmissiveTexture, Texcoord).rgb;
 #else
@@ -175,8 +191,8 @@ void main()
 #else
   float occlusion = 0.0;
 #endif
-  float metallic = MetallicFactor  * metal_roughness.b;
-  float roughness = metal_roughness.g;
+  float metallic = metal_roughness.x;
+  float roughness = metal_roughness.y;
 
   // For a single light direction:
   // vec3 brdf = cook_torrance(albedo, metallic, roughness, emissive, NdotL, NdotV, NdotH, HdotV);
diff --git a/gfx/src/renderer/renderer.c b/gfx/src/renderer/renderer.c
index 6b77ffe..3654546 100644
--- a/gfx/src/renderer/renderer.c
+++ b/gfx/src/renderer/renderer.c
@@ -29,6 +29,7 @@ bool renderer_make(Renderer* renderer, RenderBackend* render_backend) {
   assert(renderer);
   assert(render_backend);
 
+  // TODO: Load the IBL stuff lazily.
   if (!(renderer->ibl = gfx_make_ibl(render_backend))) {
     renderer_destroy(renderer, render_backend);
     return false;
diff --git a/gfx/src/util/scene.c b/gfx/src/util/scene.c
index 52812e9..35d6dd0 100644
--- a/gfx/src/util/scene.c
+++ b/gfx/src/util/scene.c
@@ -130,12 +130,14 @@
 #define UNIFORM_NORMAL_MAP                 "NormalMap"
 
 // Shader compiler defines. Must match the names in shaders.
-#define DEFINE_HAS_TEXCOORDS     "HAS_TEXCOORDS"
-#define DEFINE_HAS_NORMALS       "HAS_NORMALS"
-#define DEFINE_HAS_TANGENTS      "HAS_TANGENTS"
-#define DEFINE_HAS_NORMAL_MAP    "HAS_NORMAL_MAP"
-#define DEFINE_HAS_OCCLUSION_MAP "HAS_OCCLUSION_MAP"
-#define DEFINE_HAS_EMISSIVE_MAP  "HAS_EMISSIVE_MAP"
+#define DEFINE_HAS_TEXCOORDS              "HAS_TEXCOORDS"
+#define DEFINE_HAS_NORMALS                "HAS_NORMALS"
+#define DEFINE_HAS_TANGENTS               "HAS_TANGENTS"
+#define DEFINE_HAS_ALBEDO_MAP             "HAS_ALBEDO_MAP"
+#define DEFINE_HAS_METALLIC_ROUGHNESS_MAP "HAS_METALLIC_ROUGHNESS_MAP"
+#define DEFINE_HAS_NORMAL_MAP             "HAS_NORMAL_MAP"
+#define DEFINE_HAS_OCCLUSION_MAP          "HAS_OCCLUSION_MAP"
+#define DEFINE_HAS_EMISSIVE_MAP           "HAS_EMISSIVE_MAP"
 
 typedef enum TextureType {
   BaseColorTexture,
@@ -155,9 +157,11 @@ typedef struct MeshPermutation {
       bool has_normals   : 1;
       bool has_tangents  : 1;
       // Textures.
-      bool has_normal_map        : 1;
-      bool has_occlusion_texture : 1;
-      bool has_emissive_texture  : 1;
+      bool has_albedo_map             : 1;
+      bool has_metallic_roughness_map : 1;
+      bool has_normal_map             : 1;
+      bool has_occlusion_map          : 1;
+      bool has_emissive_map           : 1;
     };
     int32_t all;
   };
@@ -179,9 +183,11 @@ static size_t make_defines(
   check(has_texcoords, DEFINE_HAS_TEXCOORDS);
   check(has_normals, DEFINE_HAS_NORMALS);
   check(has_tangents, DEFINE_HAS_TANGENTS);
+  check(has_albedo_map, DEFINE_HAS_ALBEDO_MAP);
+  check(has_metallic_roughness_map, DEFINE_HAS_METALLIC_ROUGHNESS_MAP);
   check(has_normal_map, DEFINE_HAS_NORMAL_MAP);
-  check(has_occlusion_texture, DEFINE_HAS_OCCLUSION_MAP);
-  check(has_emissive_texture, DEFINE_HAS_EMISSIVE_MAP);
+  check(has_occlusion_map, DEFINE_HAS_OCCLUSION_MAP);
+  check(has_emissive_map, DEFINE_HAS_EMISSIVE_MAP);
 
   return next;
 }
@@ -191,10 +197,11 @@ static ShaderProgram* make_shader_permutation(
     RenderBackend* render_backend, MeshPermutation perm) {
   LOGD(
       "Compiling Cook-Torrance shader permutation: texcoords: %d, normals: "
-      "%d, tangents: %d, normal map: %d, AO map: %d, emissive map: %d",
+      "%d, tangents: %d, albedo map: %d, metallic-roughness map: %d, normal "
+      "map: %d, AO map: %d, emissive map: %d",
       perm.has_texcoords, perm.has_normals, perm.has_tangents,
-      perm.has_normal_map, perm.has_occlusion_texture,
-      perm.has_emissive_texture);
+      perm.has_albedo_map, perm.has_metallic_roughness_map, perm.has_normal_map,
+      perm.has_occlusion_map, perm.has_emissive_map);
 
   ShaderCompilerDefine defines[GFX_MAX_SHADER_COMPILER_DEFINES];
   const size_t         num_defines = make_defines(perm, defines);
@@ -436,9 +443,11 @@ static bool load_materials(
     Material** materials) {
   assert(data);
   assert(render_backend);
-  assert(load_texture_cmds);
-  assert(textures);
   assert(materials);
+  if (data->textures_count > 0) {
+    assert(load_texture_cmds);
+    assert(textures);
+  }
 
   for (cgltf_size i = 0; i < data->materials_count; ++i) {
     const cgltf_material* mat = &data->materials[i];
@@ -446,7 +455,7 @@ static bool load_materials(
     int          next_uniform = 0;
     MaterialDesc desc         = {0};
 
-    // TODO: emissive texture/factor and other material parameters.
+    // TODO: specular/glossiness and other material parameters.
     if (mat->has_pbr_metallic_roughness) {
       const cgltf_pbr_metallic_roughness* pbr = &mat->pbr_metallic_roughness;
 
@@ -579,10 +588,17 @@ static bool load_meshes(
       const cgltf_primitive* prim = &mesh->primitives[p];
       const cgltf_material*  mat  = prim->material;
 
-      MeshPermutation perm       = {0};
-      perm.has_normal_map        = mat->normal_texture.texture != 0;
-      perm.has_occlusion_texture = mat->occlusion_texture.texture != 0;
-      perm.has_emissive_texture  = mat->emissive_texture.texture != 0;
+      MeshPermutation perm   = {0};
+      perm.has_normal_map    = mat->normal_texture.texture != 0;
+      perm.has_occlusion_map = mat->occlusion_texture.texture != 0;
+      perm.has_emissive_map  = mat->emissive_texture.texture != 0;
+      // TODO: specular/glossiness and other material parameters.
+      if (mat->has_pbr_metallic_roughness) {
+        const cgltf_pbr_metallic_roughness* pbr = &mat->pbr_metallic_roughness;
+        perm.has_albedo_map = pbr->base_color_texture.texture != 0;
+        perm.has_metallic_roughness_map =
+            pbr->metallic_roughness_texture.texture != 0;
+      }
 
       GeometryDesc geometry_desc = {
           .type = from_gltf_primitive_type(prim->type)};
@@ -949,8 +965,10 @@ static bool load_scene(
     goto cleanup;
   }
 
-  load_textures_lazy(
-      data, render_backend, mstring_cstring(&directory), load_texture_cmds);
+  if (data->textures_count > 0) {
+    load_textures_lazy(
+        data, render_backend, mstring_cstring(&directory), load_texture_cmds);
+  }
 
   if (!load_materials(
           data, render_backend, load_texture_cmds, textures, materials)) {
diff --git a/gltfview/src/game.c b/gltfview/src/game.c
index 54e498b..224200d 100644
--- a/gltfview/src/game.c
+++ b/gltfview/src/game.c
@@ -189,8 +189,8 @@ static bool load_texture_debugger_scene(Game* game) {
 
 bool game_new(Game* game, int argc, const char** argv) {
   // TODO: getopt() to implement proper argument parsing.
-  const char* view_mode      = argc > 1 ? argv[1] : "";
-  const char* scene_filepath = argc > 2 ? argv[2] : DEFAULT_SCENE_FILE;
+  const char* scene_filepath = argc > 1 ? argv[1] : DEFAULT_SCENE_FILE;
+  const char* view_mode      = argc > 2 ? argv[2] : "";
 
   game->gfx = gfx_init();
   if (!game->gfx) {
@@ -234,12 +234,15 @@ void game_update(Game* game, double t, double dt) {
     usleep(1000);
     game->elapsed -= 1.0;
   }
-  Camera* camera = gfx_get_camera_camera(game->camera);
+  // TODO: Compute bounding boxes to then find a good orbit point and radius
+  // for each scene.
+  const vec3 orbit_point = vec3_make(0, 2, 0);
+  Camera*    camera      = gfx_get_camera_camera(game->camera);
   spatial3_orbit(
-      &camera->spatial, vec3_make(0, 0, 0),
-      /*radius=*/2,
+      &camera->spatial, orbit_point,
+      /*radius=*/2.5,
       /*azimuth=*/t * 0.5, /*zenith=*/0);
-  spatial3_lookat(&camera->spatial, vec3_make(0, 0, 0));
+  spatial3_lookat(&camera->spatial, orbit_point);
 }
 
 void game_render(const Game* game) {