From f6972e88b0ca738a306c419cdbaa74f7006a7241 Mon Sep 17 00:00:00 2001
From: Dave Pagurek <davepagurek@gmail.com>
Date: Thu, 4 May 2023 20:00:10 -0400
Subject: [PATCH] Default ambientMaterial to the base material color if
 unspecified

---
 src/webgl/material.js            |  1 +
 src/webgl/p5.RendererGL.js       |  3 +++
 src/webgl/shaders/phong.frag     |  5 ++++-
 test/unit/webgl/p5.RendererGL.js | 27 +++++++++++++++++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/webgl/material.js b/src/webgl/material.js
index 8c28924a09..f6d58811bf 100644
--- a/src/webgl/material.js
+++ b/src/webgl/material.js
@@ -821,6 +821,7 @@ p5.prototype.ambientMaterial = function(v1, v2, v3) {
   p5._validateParameters('ambientMaterial', arguments);
 
   const color = p5.prototype.color.apply(this, arguments);
+  this._renderer._hasSetAmbient = true;
   this._renderer.curAmbientColor = color._array;
   this._renderer._useNormalMaterial = false;
   this._renderer._enableLighting = true;
diff --git a/src/webgl/p5.RendererGL.js b/src/webgl/p5.RendererGL.js
index 4c3ae7c5b1..c3a3d1183a 100644
--- a/src/webgl/p5.RendererGL.js
+++ b/src/webgl/p5.RendererGL.js
@@ -138,6 +138,7 @@ p5.RendererGL = function(elt, pInst, isMainCanvas, attr) {
   }
   this._isBlending = false;
 
+  this._hasSetAmbient = false;
   this._useSpecularMaterial = false;
   this._useEmissiveMaterial = false;
   this._useNormalMaterial = false;
@@ -1235,6 +1236,7 @@ p5.RendererGL.prototype.push = function() {
   properties.curSpecularColor = this.curSpecularColor;
   properties.curEmissiveColor = this.curEmissiveColor;
 
+  properties._hasSetAmbient = this._hasSetAmbient;
   properties._useSpecularMaterial = this._useSpecularMaterial;
   properties._useEmissiveMaterial = this._useEmissiveMaterial;
   properties._useShininess = this._useShininess;
@@ -1526,6 +1528,7 @@ p5.RendererGL.prototype._setFillUniforms = function(fillShader) {
   }
   fillShader.setUniform('uTint', this._tint);
 
+  fillShader.setUniform('uHasSetAmbient', this._hasSetAmbient);
   fillShader.setUniform('uAmbientMatColor', this.curAmbientColor);
   fillShader.setUniform('uSpecularMatColor', this.curSpecularColor);
   fillShader.setUniform('uEmissiveMatColor', this.curEmissiveColor);
diff --git a/src/webgl/shaders/phong.frag b/src/webgl/shaders/phong.frag
index 0626793f7b..fa80efa267 100644
--- a/src/webgl/shaders/phong.frag
+++ b/src/webgl/shaders/phong.frag
@@ -2,6 +2,7 @@
 precision highp float;
 precision highp int;
 
+uniform bool uHasSetAmbient;
 uniform vec4 uSpecularMatColor;
 uniform vec4 uAmbientMatColor;
 uniform vec4 uEmissiveMatColor;
@@ -33,7 +34,9 @@ void main(void) {
     // channels by alpha to convert it to premultiplied alpha.
     : vec4(vColor.rgb * vColor.a, vColor.a);
   gl_FragColor = vec4(diffuse * baseColor.rgb + 
-                    vAmbientColor * uAmbientMatColor.rgb + 
+                    vAmbientColor * (
+                      uHasSetAmbient ? uAmbientMatColor.rgb : baseColor.rgb
+                    ) + 
                     specular * uSpecularMatColor.rgb + 
                     uEmissiveMatColor.rgb, baseColor.a);
 }
diff --git a/test/unit/webgl/p5.RendererGL.js b/test/unit/webgl/p5.RendererGL.js
index 5a736625f4..786d42b160 100644
--- a/test/unit/webgl/p5.RendererGL.js
+++ b/test/unit/webgl/p5.RendererGL.js
@@ -364,6 +364,33 @@ suite('p5.RendererGL', function() {
     });
   });
 
+  suite('materials', function() {
+    test('ambient color defaults to the fill color', function() {
+      myp5.createCanvas(100, 100, myp5.WEBGL);
+      myp5.noStroke();
+      myp5.lights();
+      myp5.fill('red');
+      myp5.sphere(25);
+      const pixel = myp5.get(50, 50);
+      expect(pixel[0]).to.equal(221);
+      expect(pixel[1]).to.equal(0);
+      expect(pixel[2]).to.equal(0);
+    });
+
+    test('ambient color can be set manually', function() {
+      myp5.createCanvas(100, 100, myp5.WEBGL);
+      myp5.noStroke();
+      myp5.lights();
+      myp5.fill('red');
+      myp5.ambientMaterial(255, 255, 255);
+      myp5.sphere(25);
+      const pixel = myp5.get(50, 50);
+      expect(pixel[0]).to.equal(221);
+      expect(pixel[1]).to.equal(128);
+      expect(pixel[2]).to.equal(128);
+    });
+  });
+
   suite('loadpixels()', function() {
     test('loadPixels color check', function(done) {
       myp5.createCanvas(100, 100, myp5.WEBGL);