Simplify mix operator to only require a single weight

asset/compiler/compiler.go

@@ -404,8 +404,7 @@ func (sc *sceneCompiler) generateMaterialTree(mat *input.Material, exprNode mate
 			return -1, err
 		}
 
-		node.Union2[0] = t.Weights[0]
-		node.Union2[1] = t.Weights[1]
+		node.Union2[0] = t.Weight
 	case material.MixMapNode:
 		node.Union1[0] = int32(material.OpMixMap)
 		node.Union1[1], err = sc.generateMaterialTree(mat, t.Expressions[0])

asset/material/material_expr.y

@@ -131,11 +131,11 @@ float_or_name: tokFLOAT { $$ = FloatNode($1) }
 float_or_texture: tokFLOAT { $$ = FloatNode($1) }
 		| tokTEXTURE { $$ = TextureNode($1) }
 
-op_spec: tokMIX tokLPAREN bxdf_or_op_spec tokCOMMA bxdf_or_op_spec tokCOMMA tokFLOAT tokCOMMA tokFLOAT tokRPAREN
+op_spec: tokMIX tokLPAREN bxdf_or_op_spec tokCOMMA bxdf_or_op_spec tokCOMMA tokFLOAT tokRPAREN
 	  { 
 	  	$$ = MixNode{ 
 	  		Expressions: [2]ExprNode{$3, $5},
-			Weights: [2]float32{$7, $9},
+			Weight: $7,
 		}
 	  }
 	  | tokMIX_MAP tokLPAREN bxdf_or_op_spec tokCOMMA bxdf_or_op_spec tokCOMMA tokTEXTURE tokRPAREN

asset/material/material_expr.y.go

@@ -312,40 +312,39 @@ const exprPrivate = 57344
 var exprTokenNames []string
 var exprStates []string
 
-const exprLast = 111
+const exprLast = 109
 
 var exprAct = [...]int{
 
 	58, 33, 64, 57, 24, 25, 26, 27, 28, 29,
-	30, 31, 32, 93, 36, 76, 70, 85, 71, 75,
+	30, 31, 32, 92, 36, 76, 70, 85, 71, 75,
 	37, 38, 39, 40, 10, 11, 12, 13, 14, 15,
 	5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
 	15, 5, 6, 7, 8, 9, 60, 56, 61, 62,
-	63, 67, 59, 72, 73, 74, 65, 66, 94, 92,
-	87, 84, 77, 68, 96, 82, 50, 49, 48, 47,
-	46, 45, 44, 43, 91, 90, 88, 83, 79, 78,
-	55, 54, 53, 86, 52, 51, 42, 97, 60, 99,
-	95, 89, 81, 80, 41, 21, 20, 98, 19, 18,
-	17, 16, 34, 2, 35, 3, 4, 23, 22, 69,
-	1,
+	63, 67, 59, 72, 73, 74, 65, 66, 93, 87,
+	84, 77, 68, 94, 82, 50, 49, 48, 47, 46,
+	45, 44, 43, 91, 90, 83, 79, 78, 55, 54,
+	53, 52, 51, 86, 42, 95, 60, 97, 89, 88,
+	81, 80, 41, 21, 20, 96, 19, 18, 17, 16,
+	34, 2, 35, 3, 4, 23, 22, 69, 1,
 }
 var exprPact = [...]int{
 
-	14, -1000, -1000, -1000, 97, 96, 95, 94, 92, 91,
+	14, -1000, -1000, -1000, 95, 94, 93, 92, 90, 89,
 	-1000, -1000, -1000, -1000, -1000, -1000, -8, 3, 3, 3,
-	3, 3, 89, 78, -1000, 64, 63, 62, 61, 60,
-	59, 58, 57, 77, -1000, -1000, -1000, 76, 74, 73,
-	72, -1000, -8, 40, 40, 40, 40, 46, 46, 53,
+	3, 3, 87, 76, -1000, 63, 62, 61, 60, 59,
+	58, 57, 56, 74, -1000, -1000, -1000, 73, 72, 71,
+	70, -1000, -8, 40, 40, 40, 40, 46, 46, 52,
 	6, 3, 3, 43, 7, -2, -1000, -1000, -1000, -1000,
-	52, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
-	-1000, -1000, 71, 70, 88, 87, 56, 69, 51, 5,
-	-1000, -1000, 82, 50, 68, 86, 67, 66, 49, -1000,
-	-5, 48, 85, 55, 80, -1000, 82, -1000, 84, -1000,
+	51, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
+	-1000, -1000, 69, 68, 86, 85, 55, 67, 50, 5,
+	-1000, -1000, 80, 49, 84, 83, 66, 65, -1000, -1000,
+	-5, 48, 54, 78, 80, -1000, 82, -1000,
 }
 var exprPgo = [...]int{
 
-	0, 110, 0, 4, 3, 2, 109, 104, 108, 107,
-	102, 1, 106,
+	0, 108, 0, 4, 3, 2, 107, 102, 106, 105,
+	100, 1, 104,
 }
 var exprR1 = [...]int{
 
@@ -358,7 +357,7 @@ var exprR2 = [...]int{
 
 	0, 1, 1, 4, 1, 1, 1, 1, 1, 1,
 	0, 1, 1, 3, 3, 3, 3, 3, 3, 3,
-	3, 3, 1, 1, 7, 1, 1, 1, 1, 10,
+	3, 3, 1, 1, 7, 1, 1, 1, 1, 8,
 	8, 6, 6, 12, 1, 1, 1,
 }
 var exprChk = [...]int{
@@ -371,8 +370,8 @@ var exprChk = [...]int{
 	9, 8, 8, 8, 8, 8, -3, -4, -2, 12,
 	6, -4, -4, -4, -5, 10, 11, -5, 10, -6,
 	10, 12, -11, -11, 12, 12, 17, 10, 8, 8,
-	5, 5, 9, 8, 10, 12, -2, 10, 8, 5,
-	8, 8, 10, 18, 10, 5, 9, 7, -2, 5,
+	5, 5, 9, 8, 10, 12, -2, 10, 5, 5,
+	8, 8, 18, 10, 9, 7, -2, 5,
 }
 var exprDef = [...]int{
 
@@ -384,8 +383,8 @@ var exprDef = [...]int{
 	0, 0, 0, 0, 0, 0, 13, 14, 22, 23,
 	0, 15, 16, 17, 18, 25, 26, 19, 20, 21,
 	27, 28, 0, 0, 0, 0, 0, 0, 0, 0,
-	31, 32, 0, 0, 0, 0, 0, 0, 0, 30,
-	0, 0, 0, 0, 0, 29, 0, 24, 0, 33,
+	31, 32, 0, 0, 0, 0, 0, 0, 29, 30,
+	0, 0, 0, 0, 0, 24, 0, 33,
 }
 var exprTok1 = [...]int{
 
@@ -862,12 +861,12 @@ exprdefault:
 			exprVAL.node = TextureNode(exprDollar[1].sVal)
 		}
 	case 29:
-		exprDollar = exprS[exprpt-10 : exprpt+1]
+		exprDollar = exprS[exprpt-8 : exprpt+1]
 		//line material_expr.y:135
 		{
 			exprVAL.node = MixNode{
 				Expressions: [2]ExprNode{exprDollar[3].node, exprDollar[5].node},
-				Weights:     [2]float32{exprDollar[7].fVal, exprDollar[9].fVal},
+				Weight:      exprDollar[7].fVal,
 			}
 		}
 	case 30:

asset/material/node.go

@@ -77,7 +77,7 @@ type BxdfParameterList []BxdfParamNode
 
 type MixNode struct {
 	Expressions [2]ExprNode
-	Weights     [2]float32
+	Weight      float32
 }
 
 type BumpMapNode struct {
@@ -227,13 +227,10 @@ func (n MixNode) Validate() error {
 		if err != nil {
 			return fmt.Errorf("mix argument %d: %v", argIndex, err)
 		}
-		if n.Weights[argIndex] < 0 || n.Weights[argIndex] > 1.0 {
-			return fmt.Errorf("mix weight %d: value must be in the [0, 1] range", argIndex)
-		}
 	}
 
-	if n.Weights[0]+n.Weights[1] != 1.0 {
-		return fmt.Errorf("mix weight sum must be equal to 1.0")
+	if n.Weight < 0 || n.Weight > 1.0 {
+		return fmt.Errorf("Mix: mix weight must be in the [0, 1] range")
 	}
 
 	return nil

asset/scene/optimized_scene.go

@@ -90,7 +90,7 @@ type MaterialNode struct {
 	// Layout:
 	// [0-3] reflectance or specularity or radiance
 	// [0-3] RGB intIORs for dispersion
-	// [0-2] blend weights
+	// [0] mix weight
 	Union2 types.Vec4
 
 	// Layout:

tracer/opencl/CL/samplers/material_sampler.cl

@@ -28,7 +28,7 @@ void matSelectNode(__global Path *path, Surface *surface, float3 inRayDir, Mater
 			case MAT_OP_MIX: 
 				// Depending on the sample, follow left or right
 				sample = randomGetSample2f(rndState);
-				node = materialNodes + (sample.x < node->mixWeights.x ? node->leftChild : node->rightChild);
+				node = materialNodes + (sample.x < node->mixWeight ? node->leftChild : node->rightChild);
 				break;
 			case MAT_OP_MIX_MAP: 
 				// Sample weight from texture

tracer/opencl/CL/types.cl

@@ -136,7 +136,7 @@ typedef struct {
 		float3 intDispersionIORs;
 
 		// mix node
-		float2 mixWeights;
+		float mixWeight;
 	};
 
 	union {