Fix gifs not animating, add another test

Author: davepagurek

src/dom/p5.MediaElement.js

@@ -66,7 +66,7 @@ class MediaElement extends Element {
         source.src = newValue;
         elt.appendChild(source);
         self.elt.src = newValue;
-        self.modified = true;
+        self._modified = true;
       }
     });
 

src/webgl/p5.Texture.js

@@ -225,6 +225,9 @@ class Texture {
         data.setModified && data.setModified(true);
       }
     } else if (this.isSrcP5Image) {
+      if (data.gifProperties) {
+        data._animateGif(this._renderer._pInst);
+      }
       // for an image, we only update if the modified field has been set,
       // for example, by a call to p5.Image.set
       if (data.isModified()) {

src/webgl/utils.js

@@ -289,9 +289,6 @@ export function setWebGLUniformValue(shader, uniform, data, getTexture, gl) {
         gl.activeTexture(gl.TEXTURE0 + uniform.samplerIndex);
         uniform.texture = data instanceof Texture ? data : getTexture(data);
         gl.uniform1i(location, uniform.samplerIndex);
-        if (uniform.texture.src.gifProperties) {
-          uniform.texture.src._animateGif(shader._renderer._pInst);
-        }
       }
       break;
     case gl.SAMPLER_CUBE:

test/unit/visual/cases/webgl.js

@@ -1211,5 +1211,17 @@ visualSuite('WebGL', function() {
       p5.image(gif, 0, 0);
       screenshot();
     });
+
+    visualTest('drawing gifs after a time delay', async function(p5, screenshot) {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      const gif = await p5.loadImage('/test/unit/assets/nyan_cat.gif');
+      p5.imageMode(p5.CENTER);
+      p5.image(gif, 0, 0);
+      p5.clear()
+      // Simulate waiting for successive draw calls
+      p5._lastRealFrameTime += 300;
+      p5.image(gif, 0, 0);
+      screenshot();
+    });
   });
 });

test/unit/visual/screenshots/WebGL/media assets/drawing gifs after a time delay/000.png

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