Merge pull request #8681 from aashu2006/fix/strands-lerp

Fix: restore lerp alias to GLSL mix in p5.strands

Author: perminder-17

src/strands/strands_api.js

@@ -284,6 +284,16 @@ export function initGlobalStrandsAPI(p5, fn, strandsContext) {
     }
   }
 
+  // Alias lerp to GLSL mix in strands context
+  const originalLerp = fn.lerp;
+  augmentFn(fn, p5, 'lerp', function (...args) {
+    if (strandsContext.active) {
+      return fn.mix(...args);
+    } else {
+      return originalLerp.apply(this, args);
+    }
+  });
+
   augmentFn(fn, p5, 'getTexture', function (...rawArgs) {
     if (strandsContext.active) {
       const { id, dimension } = strandsContext.backend.createGetTextureCall(strandsContext, rawArgs);

test/unit/visual/cases/webgl.js

@@ -1067,6 +1067,46 @@ visualSuite('WebGL', function() {
       screenshot();
     });
 
+    visualTest('lerp maps to mix in strands context', (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      // lerp should behave identically to mix inside strands
+      const shader = p5.baseColorShader().modify(() => {
+        p5.getFinalColor((color) => {
+          color = p5.lerp(
+            [1, 0, 0, 1],
+            [0, 0, 1, 1],
+            0.5
+          );
+          return color;
+        });
+      }, { p5 });
+      p5.background(0);
+      p5.shader(shader);
+      p5.noStroke();
+      p5.plane(50, 50);
+      screenshot();
+    });
+
+    visualTest('mix produces same result as lerp in strands', (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      // mix directly, should produce identical output to lerp test above
+      const shader = p5.baseColorShader().modify(() => {
+        p5.getFinalColor((color) => {
+          color = p5.mix(
+            [1, 0, 0, 1],
+            [0, 0, 1, 1],
+            0.5
+          );
+          return color;
+        });
+      }, { p5 });
+      p5.background(0);
+      p5.shader(shader);
+      p5.noStroke();
+      p5.plane(50, 50);
+      screenshot();
+    });
+
     visualSuite('auto-return for shader hooks', () => {
       visualTest('auto-returns input struct when return is omitted', (p5, screenshot) => {
         p5.createCanvas(50, 50, p5.WEBGL);

test/unit/visual/screenshots/WebGL/p5.strands/lerp maps to mix in strands context/000.png

@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}

test/unit/visual/screenshots/WebGL/p5.strands/lerp maps to mix in strands context/metadata.json

@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}