feat: Flash Action (#3142)

src/engine/Actions/Action/Flash.ts

@@ -0,0 +1,84 @@
+import { GraphicsComponent } from '../../Graphics/GraphicsComponent';
+import { Entity } from '../../EntityComponentSystem/Entity';
+import { Action, nextActionId } from '../Action';
+import { Actor } from '../../Actor';
+import { Material } from '../../Graphics/Context/material';
+import { Shader, Color } from '../../excalibur';
+
+export class Flash implements Action {
+  id = nextActionId();
+  private _graphics: GraphicsComponent;
+  private _duration: number;
+  private _stopped: boolean = false;
+  private _started: boolean = false;
+  private _entity: Entity;
+  private _material: Material | undefined;
+  private _total: number = 0;
+  private _currentDuration: number = 0;
+
+  constructor(entity: Entity, color: Color, duration: number = 1000) {
+    this._graphics = entity.get(GraphicsComponent);
+    this._duration = duration;
+    this._entity = entity;
+    this._material = entity.scene?.engine.graphicsContext.createMaterial({
+      name: 'flash-material',
+      color,
+      fragmentSource: `#version 300 es
+    
+        precision mediump float;
+        uniform float u_blend;
+        uniform sampler2D u_graphic;
+        uniform vec4 u_color;
+    
+        in vec2 v_uv; 
+        out vec4 color;
+    
+        void main() { 
+            vec4 textureColor = texture(u_graphic, v_uv); 
+            color = mix(textureColor, u_color, u_blend * textureColor.a);
+            color.rgb = color.rgb * color.a;
+        }`
+    }) as Material;
+    this._total = duration;
+  }
+
+  public update(delta: number): void {
+    if (!this._started) {
+      this._started = true;
+      this._total = this._duration;
+      this._currentDuration = this._duration;
+      (this._entity as Actor).graphics.material = this._material as Material;
+    }
+    if (!this._graphics) {
+      return;
+    }
+
+    this._currentDuration -= delta;
+
+    if (this._graphics) {
+      this._material?.update((shader: Shader) => {
+        shader.trySetUniformFloat('u_blend', this._currentDuration / this._total);
+      });
+    }
+
+    if (this.isComplete()) {
+      (this._entity as Actor).graphics.material = null;
+    }
+  }
+
+  public isComplete(): boolean {
+    return this._stopped || this._currentDuration <= 0;
+  }
+
+  public stop(): void {
+    if (this._graphics) {
+      this._graphics.visible = true;
+    }
+    this._stopped = true;
+  }
+
+  public reset() {
+    this._started = false;
+    this._stopped = false;
+  }
+}

src/engine/Actions/Index.ts

@@ -22,6 +22,7 @@ export * from './Action/RotateTo';
 export * from './Action/ScaleBy';
 export * from './Action/ScaleTo';
 export * from './Action/Delay';
+export * from './Action/Flash';
 
 export * from './ActionsComponent';
 export * from './ActionsSystem';