From 8925bd867e1a8791801698b1abaec4a46180656e Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Thu, 12 Aug 2021 20:25:25 -0400
Subject: graphics: Always use normal/ambient/etc. maps.

If models don't specify their own textures, use noop textures as
appropriate.
---
 data/shaders/pbr-frag.glsl | 80 ++++++++++++++++------------------------------
 1 file changed, 27 insertions(+), 53 deletions(-)

(limited to 'data/shaders/pbr-frag.glsl')

diff --git a/data/shaders/pbr-frag.glsl b/data/shaders/pbr-frag.glsl
index 478c40a..c474981 100644
--- a/data/shaders/pbr-frag.glsl
+++ b/data/shaders/pbr-frag.glsl
@@ -2,19 +2,13 @@
 
 struct Material {
   vec3 baseColorFactor;
-  bool baseColorTextureEnabled;
   int baseColorTexcoord;
   float metallicFactor;
   float roughnessFactor;
-  bool metallicRoughnessTextureEnabled;
   int metallicRoughnessTexcoord;
-  vec3 normalFactor;
-  bool normalTextureEnabled;
   int normalTexcoord;
-  bool occlusionTextureEnabled;
   int occlusionTexcoord;
   vec3 emissiveFactor;
-  bool emissiveTextureEnabled;
   int emissiveTexcoord;
   int alphaMode;
   float alphaCutoff;
@@ -142,34 +136,25 @@ vec3 toneMap(vec3 color) {
 
 float materialMetallic() {
   float m = material.metallicFactor;
-
-  if(material.metallicRoughnessTextureEnabled) {
-    m *= texture(metallicRoughnessTexture,
-                 texcoord(material.metallicRoughnessTexcoord)).b;
-  }
-
+  m *= texture(metallicRoughnessTexture,
+               texcoord(material.metallicRoughnessTexcoord)).b;
   return m;
 }
 
 float materialRoughness() {
   float r = material.roughnessFactor;
 
-  if(material.metallicRoughnessTextureEnabled) {
-    r *= texture(metallicRoughnessTexture,
-                 texcoord(material.metallicRoughnessTexcoord)).g;
-  }
+  r *= texture(metallicRoughnessTexture,
+               texcoord(material.metallicRoughnessTexcoord)).g;
 
   return r;
 }
 
 vec4 materialAlbedo() {
-  vec4 color = vec4(0.0, 0.0, 1.0, 1.0);
-
-  if(material.baseColorTextureEnabled) {
-    vec4 texColor = texture(baseColorTexture,
-                            texcoord(material.baseColorTexcoord));
-    color = sRGBtoLinear(texColor);
-  }
+  vec4 color = vec4(1.0, 1.0, 1.0, 1.0);
+  vec4 texColor = texture(baseColorTexture,
+                          texcoord(material.baseColorTexcoord));
+  color = sRGBtoLinear(texColor);
 
   color *= vec4(material.baseColorFactor, 1.0);
 
@@ -183,44 +168,33 @@ vec4 materialAlbedo() {
 vec3 materialEmissive() {
   vec3 color = vec3(0.0);
 
-  if(material.emissiveTextureEnabled) {
-    vec4 texColor = texture(emissiveTexture,
-                            texcoord(material.emissiveTexcoord));
-    color = sRGBtoLinear(texColor).rgb;
-  }
+  vec4 texColor = texture(emissiveTexture,
+                          texcoord(material.emissiveTexcoord));
+  color = sRGBtoLinear(texColor).rgb;
 
   return color * material.emissiveFactor;
 }
 
 vec3 materialOcclusion() {
-  if(material.occlusionTextureEnabled) {
-    return vec3(texture(occlusionTexture,
-                        texcoord(material.occlusionTexcoord)).r);
-  } else {
-    return vec3(1.0);
-  }
+  return vec3(texture(occlusionTexture,
+                      texcoord(material.occlusionTexcoord)).r);
 }
 
 vec3 materialNormal() {
-  if(material.normalTextureEnabled) {
-    // See: http://www.thetenthplanet.de/archives/1180
-    vec2 t = texcoord(material.normalTexcoord);
-    vec3 tangentNormal = texture(normalTexture, t).xyz * 2.0 - 1.0;
-
-    vec3 q1 = dFdx(fragWorldPos);
-    vec3 q2 = dFdy(fragWorldPos);
-    vec2 st1 = dFdx(fragTexcoord0);
-    vec2 st2 = dFdy(fragTexcoord0);
-
-    vec3 N = normalize(fragNormal);
-    vec3 T = normalize(q1 * st2.t - q2 * st1.t);
-    vec3 B = -normalize(cross(N, T));
-    mat3 TBN = mat3(T, B, N);
-
-    return normalize(TBN * tangentNormal);
-  } else {
-    return normalize(fragNormal);
-  }
+  // See: https://github.com/SaschaWillems/Vulkan-glTF-PBR/blob/master/data/shaders/pbr_khr.frag
+  // See: http://www.thetenthplanet.de/archives/1180
+  vec2 uv = texcoord(material.normalTexcoord);
+  vec3 tangentNormal = texture(normalTexture, uv).xyz * 2.0 - 1.0;
+  vec3 q1 = dFdx(fragWorldPos);
+  vec3 q2 = dFdy(fragWorldPos);
+  vec2 st1 = dFdx(uv);
+  vec2 st2 = dFdy(uv);
+  vec3 N = normalize(fragNormal);
+  vec3 T = normalize(q1 * st2.t - q2 * st1.t);
+  vec3 B = -normalize(cross(N, T));
+  mat3 TBN = mat3(T, B, N);
+
+  return normalize(TBN * tangentNormal);
 }
 
 vec3 lightDirection(Light light) {
-- 
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