From 62110ea34481391534645f1027108237bae050a4 Mon Sep 17 00:00:00 2001
From: Justin Young <62815737+jyoung4242@users.noreply.github.com>
Date: Wed, 31 Jul 2024 15:39:18 -0400
Subject: [PATCH] feat: Flash Action (#3142)

---
 src/engine/Actions/Action/Flash.ts | 84 ++++++++++++++++++++++++++++++
 src/engine/Actions/Index.ts        |  1 +
 2 files changed, 85 insertions(+)
 create mode 100644 src/engine/Actions/Action/Flash.ts

diff --git a/src/engine/Actions/Action/Flash.ts b/src/engine/Actions/Action/Flash.ts
new file mode 100644
index 000000000..45b39b47d
--- /dev/null
+++ b/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;
+  }
+}
diff --git a/src/engine/Actions/Index.ts b/src/engine/Actions/Index.ts
index 1e7491eba..eff76c4c7 100644
--- a/src/engine/Actions/Index.ts
+++ b/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';