Feature: Cross products with two constant 3D vectors are simplified.

e.g.
"vec3 v = cross(vec3(1, 2, 3), vec3(4, 5, 6));" => "vec3 v = vec3(-3, 6, -3);"

Author: DeanEdisGG

ShaderShrinker/Shrinker.Parser/Optimizations/PerformArithmeticExtension.cs

@@ -178,20 +178,7 @@ public static bool PerformArithmetic(this SyntaxNode rootNode)
                         continue;
 
                     var mag = Math.Sqrt(nums.Sum(o => o * o));
-
-                    // Squash vecN(n, n, n, ...) down to vecN(n)
-                    if (nums.Count > 1 && nums.Distinct().Count() == 1)
-                        nums = new List<double> { nums.First() };
-
-                    var newVectorNumNodes = nums.SelectMany(o => new[]
-                    {
-                        new GenericSyntaxNode(new CommaToken()),
-                        new GenericSyntaxNode(FloatToken.From(o / mag, MaxDp).AsIntIfPossible())
-                    }).Skip(1);
-
-                    var newVectorBrackets = new RoundBracketSyntaxNode(newVectorNumNodes);
-                    var newVectorNode = new GenericSyntaxNode(normalizeNode.Params.Children.First().Token.Content);
-                    normalizeNode.ReplaceWith(newVectorNode).InsertNextSibling(newVectorBrackets);
+                    ReplaceNodeWithVector(normalizeNode, nums.Select(o => o / mag).ToList());
                     didChange = true;
                 }
 
@@ -234,6 +221,33 @@ public static bool PerformArithmetic(this SyntaxNode rootNode)
                     didChange = true;
                 }
 
+                // cross(vecN, vecN) => vecN(...)
+                foreach (var crossNode in functionCalls
+                             .Where(o => o.Name == "cross" && o.Params.Children.Count(n => (n.Token as TypeToken)?.IsVector() == true) == 2)
+                             .ToList())
+                {
+                    var crossParams = crossNode.Params.GetCsv().ToList();
+                    var vectors = crossParams.Select(o => o.First()).Where(o => (o.Token as TypeToken)?.IsVector() == true).ToList();
+                    var nums = vectors.Select(GetVectorNumericCsv).ToList();
+
+                    if (nums.Count(o => o != null) != 2)
+                        continue; // Not a cross product of two 'simple' numeric vectors.
+
+                    if (nums.Any(o => o.Count != 3))
+                        continue; // Not a pair of 3D vectors.
+
+                    // Both args are vectors and simple numeric - We can calculate the result.
+                    ReplaceNodeWithVector(
+                                          crossNode,
+                                          new[]
+                                          {
+                                              nums[0][1] * nums[1][2] - nums[1][1] * nums[0][2],
+                                              nums[1][0] * nums[0][2] - nums[0][0] * nums[1][2],
+                                              nums[0][0] * nums[1][1] - nums[1][0] * nums[0][1]
+                                          });
+                    didChange = true;
+                }
+
                 // Constant math/trig functions => <the result>
                 var mathOp = new List<Tuple<string, Func<double, double>>>
                 {
@@ -440,6 +454,25 @@ public static bool PerformArithmetic(this SyntaxNode rootNode)
             return repeatSimplifications;
         }
 
+        private static void ReplaceNodeWithVector(SyntaxNode node, ICollection<double> vectorElements)
+        {
+            // Squash vecN(n, n, n, ...) down to vecN(n)?
+            var nums = vectorElements.ToList();
+            if (nums.Count > 1 && nums.Distinct().Count() == 1)
+                nums = new List<double> { nums.First() };
+
+            var bracketContent = nums.SelectMany(
+                                                 o => new[]
+                                                 {
+                                                     new GenericSyntaxNode(new CommaToken()),
+                                                     new GenericSyntaxNode(FloatToken.From(o, MaxDp).AsIntIfPossible())
+                                                 }).Skip(1);
+
+            node
+                .ReplaceWith(new GenericSyntaxNode(new TypeToken($"vec{vectorElements.Count}")))
+                .InsertNextSibling(new RoundBracketSyntaxNode(bracketContent));
+        }
+
         private static List<double> GetVectorNumericCsv(SyntaxNode vectorNode)
         {
             if (vectorNode.Next is not RoundBracketSyntaxNode brackets || !brackets.IsNumericCsv())

ShaderShrinker/Shrinker.Parser/SyntaxNodes/FileSyntaxNode.cs

@@ -533,7 +533,7 @@ private void FindVariableDeclarations()
                 // Create declaration node.
                 var terminatorNode = namesAndValues.Last().Last().Next;
                 var declNode = new VariableDeclarationSyntaxNode(typeNode);
-                var assignments = namesAndValues.Select(o => new VariableAssignmentSyntaxNode(new GenericSyntaxNode(o.First().Token.Content), o.Count > 1 ? o.Skip(1).ToList() : null)).OfType<SyntaxNode>().ToArray();
+                var assignments = namesAndValues.Select(o => new VariableAssignmentSyntaxNode(new GenericSyntaxNode(o.First().Token.Clone()), o.Count > 1 ? o.Skip(1).ToList() : null)).OfType<SyntaxNode>().ToArray();
                 declNode.Adopt(assignments);
 
                 // Replace original nodes with the new versions.

ShaderShrinker/UnitTests/TestFiles/GolfedReference/Temple.glsl

@@ -1,4 +1,4 @@
-// Processed by 'GLSL Shader Shrinker' (Shrunk by 1,417 characters)
+// Processed by 'GLSL Shader Shrinker' (Shrunk by 1,390 characters)
 // (https://github.com/deanthecoder/GLSLShaderShrinker)
 
 #define v3	vec3
@@ -149,14 +149,13 @@ vec3 ve(v3 m, v2 w) {
 }
 
 void mainImage(out vec4 v, v2 w) {
+	const v3 u = v3(-.59359, -.31163, .74198),
+	         Y = v3(42.563, 68.101, 59.588);
 	v2 z = v2(0),
 	   UV = (w - .5 * iR.xy) / iR.y;
 	v3 p,
-	   u = v3(-.59359, -.31163, .74198),
 	   M = NM(cross(v3(0, 1, 0), u)),
 	   K = NM(u + UV.x * M + UV.y * cross(u, M)),
-	   Z = v3(.42563, .68101, .59588),
-	   Y = Z * 1e2,
 	   m = v3(0);
 	_f d = 0.;
 	for (int steps = min(iFrame, 0); steps < 200; steps++) {
@@ -189,13 +188,13 @@ void mainImage(out vec4 v, v2 w) {
 		else if (z.y < 3.5) {
 			C = v3(.002, .02, .04);
 			U = k(p, Y, 1.);
-			_f tt = S(p);
-			C *= 1. * (1. + SS(30., 0., tt));
-			C *= 1. * (1. + SS(5., 0., tt));
+			_f Z = S(p);
+			C *= 1. * (1. + SS(30., 0., Z));
+			C *= 1. * (1. + SS(5., 0., Z));
 		}
 
-		X = max(0., dot(Z, n)) * 6.;
-		g = .2 * max(0., dot(Z * v3(-1, 0, -1), n));
+		X = max(0., dot(v3(.42563, .68101, .59588), n)) * 6.;
+		g = .2 * max(0., dot(v3(-.42563, 0, -.59588), n));
 		V = (.6 + .5 * n.y) * .05;
 		m = C * X * v3(1.64, 1.27, .99) * U;
 		m += C * g * v3(1.64, 1.27, .99) * H;

ShaderShrinker/UnitTests/TestFiles/SimplifiedReference/Temple.glsl

@@ -1,4 +1,4 @@
-// Processed by 'GLSL Shader Shrinker' (Shrunk by 412 characters)
+// Processed by 'GLSL Shader Shrinker' (Shrunk by 414 characters)
 // (https://github.com/deanthecoder/GLSLShaderShrinker)
 
 #define SKYCOL	vec3(.6, .8, .9)
@@ -142,14 +142,13 @@ vec3 vignette(vec3 col, vec2 fragCoord) {
 }
 
 void mainImage(out vec4 fragColor, vec2 fragCoord) {
+	const vec3 forward = vec3(-.59359, -.31163, .74198),
+	           sunPos = vec3(42.563, 68.101, 59.588);
 	vec2 hit = vec2(0),
 	     uv = (fragCoord - .5 * iResolution.xy) / iResolution.y;
 	vec3 p,
-	     forward = vec3(-.59359, -.31163, .74198),
 	     right = normalize(cross(vec3(0, 1, 0), forward)),
 	     rayDir = normalize(forward + uv.x * right + uv.y * cross(forward, right)),
-	     sunPosUnit = vec3(.42563, .68101, .59588),
-	     sunPos = sunPosUnit * 1e2,
 	     col = vec3(0);
 	float d = 0.;
 	for (int steps = min(iFrame, 0); steps < 200; steps++) {
@@ -187,8 +186,8 @@ void mainImage(out vec4 fragColor, vec2 fragCoord) {
 			mat *= 1. * (1. + smoothstep(5., 0., terrainDist));
 		}
 
-		sun = max(0., dot(sunPosUnit, n)) * 6.;
-		back = .2 * max(0., dot(sunPosUnit * vec3(-1, 0, -1), n));
+		sun = max(0., dot(vec3(.42563, .68101, .59588), n)) * 6.;
+		back = .2 * max(0., dot(vec3(-.42563, 0, -.59588), n));
 		sky = (.6 + .5 * n.y) * .05;
 		col = mat * sun * vec3(1.64, 1.27, .99) * sha;
 		col += mat * back * vec3(1.64, 1.27, .99) * occ;

ShaderShrinker/UnitTests/VectorArithmeticTests.cs

@@ -266,7 +266,7 @@ public void CheckArithmeticWithFractFunction()
         }
 
         [Test, Sequential]
-        public void CheckArithmeticWithSingleIndexDotFunction(
+        public void CheckArithmeticWithDotFunction(
             [Values("vec3 v; float f = dot(vec3(0, 0, 1), v);|vec3 v; float f = v.z;",
                     "vec3 v; float f = dot(vec3(0, 1, 0), v);|vec3 v; float f = v.y;",
                     "vec3 v; float f = dot(vec3(1, 0, 0), v);|vec3 v; float f = v.x;",
@@ -291,6 +291,25 @@ public void CheckArithmeticWithSingleIndexDotFunction(
             Assert.That(rootNode.ToCode().ToSimple(), Is.EqualTo(expected));
         }
 
+        [Test, Sequential]
+        public void CheckArithmeticWithCrossFunction(
+            [Values("vec3 v = cross(vec3(1, 2, 3), vec3(4, 5, 6));|vec3 v = vec3(-3, 6, -3);")] string code)
+        {
+            var input = code.Split('|')[0];
+            var expected = code.Split('|')[1];
+
+            var lexer = new Lexer();
+            lexer.Load(input);
+
+            var options = CustomOptions.None();
+            options.PerformArithmetic = true;
+            var rootNode = new Parser(lexer)
+                .Parse()
+                .Simplify(options);
+
+            Assert.That(rootNode.ToCode().ToSimple(), Is.EqualTo(expected));
+        }
+
         [Test, Sequential]
         public void CheckArithmeticWithTrigFunctions(
             [Values("float f = sin(3.141);",