1 files changed, 57 insertions, 41 deletions

diff --git a/shaders/cook_torrance.frag b/shaders/cook_torrance.frag
index 9ff5a8d..f6c6048 100644
--- a/shaders/cook_torrance.frag
+++ b/shaders/cook_torrance.frag
@@ -10,19 +10,26 @@ uniform float MetallicFactor;
 uniform float RoughnessFactor;
 uniform vec3  EmissiveFactor;
 
-#ifdef HAS_ALBEDO_MAP
+#if HAS_TRANSPARENCY
+#define ALPHA_MODE_MASK  1
+#define ALPHA_MODE_BLEND 2
+uniform int   AlphaMode;
+uniform float AlphaCutoff;
+#endif
+
+#if HAS_ALBEDO_MAP
 uniform sampler2D BaseColorTexture;
 #endif
-#ifdef HAS_METALLIC_ROUGHNESS_MAP
+#if HAS_METALLIC_ROUGHNESS_MAP
 uniform sampler2D MetallicRoughnessTexture;
 #endif
-#ifdef HAS_EMISSIVE_MAP
+#if HAS_EMISSIVE_MAP
 uniform sampler2D EmissiveTexture;
 #endif
-#ifdef HAS_OCCLUSION_MAP
+#if HAS_OCCLUSION_MAP
 uniform sampler2D AmbientOcclusionTexture;
 #endif
-#ifdef HAS_NORMAL_MAP
+#if HAS_NORMAL_MAP
 uniform sampler2D NormalMap;
 #endif
 
@@ -37,13 +44,13 @@ uniform vec3 CameraPosition; // World space.
 
 // World-space position, normal and tangent.
 in vec3 Position;
-#ifdef HAS_NORMALS
+#if HAS_NORMALS
 in vec3 Normal;
 #endif
-#ifdef HAS_TANGENTS
+#if HAS_TANGENTS
 in vec4 Tangent;
 #endif
-#ifdef HAS_TEXCOORDS
+#if HAS_TEXCOORDS
 in vec2 Texcoord;
 #endif
 
@@ -61,7 +68,7 @@ layout (location = 0) out vec4 Colour;
 #if defined(HAS_NORMAL_MAP) && (defined(HAS_TANGENTS) || defined(HAS_TEXCOORDS))
 vec3 get_ws_normal(vec3 normalWs, vec3 normalMapSample) {
   vec3 N = normalize(Normal);
-#ifdef HAS_TANGENTS
+#if HAS_TANGENTS
   //vec3 T = normalize(tangent.xyz - dot(tangent.xyz, N) * N);
   vec3 T = Tangent.xyz;
   vec3 B = Tangent.w * cross(N, T);
@@ -145,8 +152,8 @@ vec3 cook_torrance_IBL(
     vec3 albedo, float metallic, float roughness, float occlusion,
     float NdotV,
     vec3 irradiance, vec3 prefiltered_env, vec2 BRDF_env) {
-  vec3 F0 = mix(vec3(0.04), albedo, metallic);
-  vec3  F = fresnel_schlick_roughness(F0, NdotV, roughness);
+  vec3 F0 = mix(vec3(0.04), albedo, metallic); // albedo = F0 for metals
+  vec3 F  = fresnel_schlick_roughness(F0, NdotV, roughness);
   vec3 Kd = (vec3(1.0) - F) * (1.0 - metallic);
   // A non-HDR environment map essentially has the 1/pi baked in as it does not
   // use physical units. See:
@@ -159,36 +166,19 @@ vec3 cook_torrance_IBL(
 
 void main()
 {
-  // TODO: Also use the specular F0 map from the model, and emissive. Make sure
-  // to use all maps.
-  // https://sketchfab.com/models/b81008d513954189a063ff901f7abfe4
-#ifdef HAS_NORMAL_MAP
-  vec3 normalMapSample = texture(NormalMap, Texcoord).xyz * 2.0 - 1.0;
-  vec3 N = get_ws_normal(Normal, normalMapSample);
-#elif HAS_NORMALS
-  vec3 N = normalize(Normal);
-#endif
-  vec3 V = normalize(CameraPosition - Position);
-  vec3 R = reflect(-V, N);
-  // Not needed for IBL.
-  //vec3 L = N;
-  //vec3 H = normalize(L + V);
-
-  float NdotV = max(0.0, dot(N, V));
-  // Not needed for IBL.
-  //float NdotL = max(0.0, dot(N,L));
-  //float NdotH = max(0.0, dot(N,H));
-  //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.
   // TODO: Other factors.
-#ifdef HAS_ALBEDO_MAP
-  vec3 albedo = vec3(BaseColorFactor) * texture(BaseColorTexture, Texcoord).rgb;
+#if HAS_ALBEDO_MAP
+  vec4 base_colour = vec4(BaseColorFactor) * texture(BaseColorTexture, Texcoord);
 #else
-  vec3 albedo = vec3(BaseColorFactor);
+  vec4 base_colour = vec4(BaseColorFactor);
 #endif
-#ifdef HAS_METALLIC_ROUGHNESS_MAP
+  vec3 albedo = base_colour.rgb;
+#if HAS_TRANSPARENCY
+  if ((AlphaMode == ALPHA_MODE_MASK) && (base_colour.a < AlphaCutoff)) {
+    discard;
+  }
+#endif
+#if HAS_METALLIC_ROUGHNESS_MAP
   // Spec: "Its green channel contains roughness values and its blue channel
   // contains metalness values."
   vec2 metal_roughness
@@ -197,12 +187,12 @@ void main()
 #else
   vec2 metal_roughness = vec2(MetallicFactor, RoughnessFactor);
 #endif
-#ifdef HAS_EMISSIVE_MAP
+#if HAS_EMISSIVE_MAP
   vec3 emissive = EmissiveFactor * texture(EmissiveTexture, Texcoord).rgb;
 #else
   vec3 emissive = EmissiveFactor;
 #endif
-#ifdef HAS_OCCLUSION_MAP
+#if HAS_OCCLUSION_MAP
   float occlusion = texture(AmbientOcclusionTexture, Texcoord).r;
 #else
   float occlusion = 1.0;
@@ -210,6 +200,32 @@ void main()
   float metallic  = metal_roughness.x;
   float roughness = metal_roughness.y;
 
+  // TODO: Also use the specular F0 map from the model, and emissive. Make sure
+  // to use all maps.
+  // https://sketchfab.com/models/b81008d513954189a063ff901f7abfe4
+#if HAS_NORMAL_MAP
+  // Spec: "After dequantization, texel values MUST be mapped as follows:
+  //   red   [0.0 .. 1.0] to X [-1 .. 1],
+  //   green [0.0 .. 1.0] to Y [-1 .. 1],
+  //   blue  (0.5 .. 1.0] to Z ( 0 .. 1].
+  // Normal textures SHOULD NOT contain blue values less than or equal to 0.5."
+  vec3 normalMapSample = texture(NormalMap, Texcoord).xyz * 2.0 - 1.0;
+  vec3 N = get_ws_normal(Normal, normalMapSample);
+#elif HAS_NORMALS
+  vec3 N = normalize(Normal);
+#endif
+  vec3 V = normalize(CameraPosition - Position);
+  vec3 R = reflect(-V, N);
+  // Not needed for IBL.
+  //vec3 L = N;
+  //vec3 H = normalize(L + V);
+
+  float NdotV = max(0.0, dot(N, V));
+  // Not needed for IBL.
+  //float NdotL = max(0.0, dot(N,L));
+  //float NdotH = max(0.0, dot(N,H));
+  //float HdotV = clamp(dot(H,V), 0.0, 1.0);  // Clamp to prevent black spots.
+
   // For a single light direction:
   // vec3 brdf = cook_torrance(albedo, metallic, roughness, NdotL, NdotV, NdotH, HdotV);
   // vec3 Li = texture(Sky, N).rgb;
@@ -268,5 +284,5 @@ void main()
   //   //colour = B * 0.5 + 0.5;
   // }
 
-  Colour = vec4(colour, 1.0);
+  Colour = vec4(colour, base_colour.a);
 }