Add support for 2 additional material variables

NEW_RELEASE_NOTES.md

@@ -13,3 +13,4 @@ appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).
   dark fringes to appear (recompile materials)
 - Allow glTF materials with transmission/volume extensions to choose their alpha mode
   instead of forcing `MASKED`
+- Add support for 2 additional material variables [⚠️ **Recompile materials**]

android/filamat-android/src/main/java/com/google/android/filament/filamat/MaterialBuilder.java

@@ -102,7 +102,9 @@ public class MaterialBuilder {
         CUSTOM0,
         CUSTOM1,
         CUSTOM2,
-        CUSTOM3
+        CUSTOM3,
+        CUSTOM4,
+        CUSTOM5
     }
 
     public enum VertexAttribute {

docs/Materials.md.html

@@ -1299,7 +1299,7 @@ Type
 :    array of `string`
 
 Value
-:     Up to 4 strings, each must be a valid GLSL identifier.
+:     Up to 6 strings, each must be a valid GLSL identifier.
 
 Description
 :     Defines custom interpolants (or variables) that are output by the material's vertex shader.

libs/filamat/include/filamat/MaterialBuilder.h

@@ -208,12 +208,14 @@ public:
     MaterialBuilder(MaterialBuilder&& rhs) noexcept = default;
     MaterialBuilder& operator=(MaterialBuilder&& rhs) noexcept = default;
 
-    static constexpr size_t MATERIAL_VARIABLES_COUNT = 4;
+    static constexpr size_t MATERIAL_VARIABLES_COUNT = 6;
     enum class Variable : uint8_t {
         CUSTOM0,
         CUSTOM1,
         CUSTOM2,
-        CUSTOM3
+        CUSTOM3,
+        CUSTOM4,
+        CUSTOM5
         // when adding more variables, make sure to update MATERIAL_VARIABLES_COUNT
     };
 

libs/filamat/src/MaterialBuilder.cpp

@@ -205,6 +205,8 @@ MaterialBuilder& MaterialBuilder::variable(Variable v, const char* name) noexcep
         case Variable::CUSTOM1:
         case Variable::CUSTOM2:
         case Variable::CUSTOM3:
+        case Variable::CUSTOM4:
+        case Variable::CUSTOM5:
             assert(size_t(v) < MATERIAL_VARIABLES_COUNT);
             mVariables[size_t(v)] = CString(name);
             break;

shaders/src/varyings.glsl

@@ -2,34 +2,37 @@
 // Varyings
 //------------------------------------------------------------------------------
 
-LAYOUT_LOCATION(4) VARYING highp vec4 vertex_worldPosition;
+// Varying locations [0, MaterialBuilder::MATERIAL_VARIABLES_COUNT) are reserved for user material
+// variables.
+
+LAYOUT_LOCATION(6) VARYING highp vec4 vertex_worldPosition;
 
 #if defined(HAS_ATTRIBUTE_TANGENTS)
-LAYOUT_LOCATION(5) SHADING_INTERPOLATION VARYING mediump vec3 vertex_worldNormal;
+LAYOUT_LOCATION(7) SHADING_INTERPOLATION VARYING mediump vec3 vertex_worldNormal;
 #if defined(MATERIAL_NEEDS_TBN)
-LAYOUT_LOCATION(6) SHADING_INTERPOLATION VARYING mediump vec4 vertex_worldTangent;
+LAYOUT_LOCATION(8) SHADING_INTERPOLATION VARYING mediump vec4 vertex_worldTangent;
 #endif
 #endif
 
-LAYOUT_LOCATION(7) VARYING highp vec4 vertex_position;
+LAYOUT_LOCATION(9) VARYING highp vec4 vertex_position;
 
 #if defined(FILAMENT_HAS_FEATURE_INSTANCING)
-LAYOUT_LOCATION(8) flat VARYING highp int instance_index;
+LAYOUT_LOCATION(10) flat VARYING highp int instance_index;
 highp int logical_instance_index;
 #endif
 
 #if defined(HAS_ATTRIBUTE_COLOR)
-LAYOUT_LOCATION(9) VARYING mediump vec4 vertex_color;
+LAYOUT_LOCATION(11) VARYING mediump vec4 vertex_color;
 #endif
 
 #if defined(HAS_ATTRIBUTE_UV0) && !defined(HAS_ATTRIBUTE_UV1)
-LAYOUT_LOCATION(10) VARYING highp vec2 vertex_uv01;
+LAYOUT_LOCATION(12) VARYING highp vec2 vertex_uv01;
 #elif defined(HAS_ATTRIBUTE_UV1)
-LAYOUT_LOCATION(10) VARYING highp vec4 vertex_uv01;
+LAYOUT_LOCATION(12) VARYING highp vec4 vertex_uv01;
 #endif
 
 #if defined(VARIANT_HAS_SHADOWING) && defined(VARIANT_HAS_DIRECTIONAL_LIGHTING)
-LAYOUT_LOCATION(11) VARYING highp vec4 vertex_lightSpacePosition;
+LAYOUT_LOCATION(13) VARYING highp vec4 vertex_lightSpacePosition;
 #endif
 
 // Note that fragColor is an output and is not declared here; see main.fs and depth_main.fs

tools/matc/src/matc/ParametersProcessor.cpp

@@ -66,6 +66,8 @@ static MaterialBuilder::Variable intToVariable(size_t i) noexcept {
         case 1:  return MaterialBuilder::Variable::CUSTOM1;
         case 2:  return MaterialBuilder::Variable::CUSTOM2;
         case 3:  return MaterialBuilder::Variable::CUSTOM3;
+        case 4:  return MaterialBuilder::Variable::CUSTOM4;
+        case 5:  return MaterialBuilder::Variable::CUSTOM5;
         default: return MaterialBuilder::Variable::CUSTOM0;
     }
 }
@@ -607,8 +609,9 @@ static bool processVariables(MaterialBuilder& builder, const JsonishValue& value
     const JsonishArray* jsonArray = value.toJsonArray();
     const auto& elements = jsonArray->getElements();
 
-    if (elements.size() > 4) {
-        std::cerr << "variables: Max array size is 4." << std::endl;
+    if (elements.size() > MaterialBuilder::MATERIAL_VARIABLES_COUNT) {
+        std::cerr << "variables: Max array size is " << MaterialBuilder::MATERIAL_VARIABLES_COUNT
+                  << "." << std::endl;
         return false;
     }