Playing with pipeline to display outline

front/src/Phaser/Shaders/OutlinePipeline.ts

@@ -0,0 +1,61 @@
+export class OutlinePipeline extends Phaser.Renderer.WebGL.Pipelines.TextureTintPipeline
+{
+
+    // the unique id of this pipeline
+    public static readonly KEY = 'Outline';
+
+    /**
+     * @param {Phaser.Game} game - the controller of the game instance
+     */
+    constructor(game: Phaser.Game)
+    {
+        super({
+            game: game,
+            renderer: game.renderer,
+            fragShader: `
+        precision mediump float;
+
+        uniform sampler2D uMainSampler;
+        uniform vec2 uTextureSize;
+
+        varying vec2 outTexCoord;
+        varying float outTintEffect;
+        varying vec4 outTint;
+
+        void main(void) 
+        {
+          vec4 texture = texture2D(uMainSampler, outTexCoord);
+          vec4 texel = vec4(outTint.rgb * outTint.a, outTint.a);
+          vec4 color = texture;
+
+          if (outTintEffect == 0.0)
+          {
+            color = texture * texel;
+          }
+          else if (outTintEffect == 1.0)
+          {
+            color.rgb = mix(texture.rgb, outTint.rgb * outTint.a, texture.a);
+            color.a = texture.a * texel.a;
+          }
+          else if (outTintEffect == 2.0)
+          {
+            color = texel;
+          }
+
+          vec2 onePixel = vec2(1.0, 1.0) / uTextureSize;
+          float upAlpha = texture2D(uMainSampler, outTexCoord + vec2(0.0, onePixel.y)).a;
+          float leftAlpha = texture2D(uMainSampler, outTexCoord + vec2(-onePixel.x, 0.0)).a;
+          float downAlpha = texture2D(uMainSampler, outTexCoord + vec2(0.0, -onePixel.y)).a;
+          float rightAlpha = texture2D(uMainSampler, outTexCoord + vec2(onePixel.x, 0.0)).a;
+
+          if (texture.a == 0.0 && max(max(upAlpha, downAlpha), max(leftAlpha, rightAlpha)) == 1.0) 
+          {
+            color = vec4(1.0, 1.0, 1.0, 1.0);
+          }
+
+          gl_FragColor = color;
+        }
+      `
+        });
+    }
+}