Add files

src/graphics/graphics-library/frame-buffer/frame-buffer.ts

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+import { vec2 } from 'gl-matrix';
+import { settings } from '../../settings';
+
+export abstract class FrameBuffer {
+  public renderScale = 1;
+  public enableHighDpiRendering = settings.enableHighDpiRendering;
+
+  protected size = vec2.create();
+
+  // null means the default framebuffer
+  protected frameBuffer: WebGLFramebuffer | null = null;
+
+  constructor(protected gl: WebGL2RenderingContext) {}
+
+  public bindAndClear(colorInput?: WebGLTexture) {
+    this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, this.frameBuffer);
+
+    if (colorInput) {
+      this.gl.bindTexture(this.gl.TEXTURE_2D, colorInput);
+    }
+
+    this.gl.viewport(0, 0, this.size.x, this.size.y);
+    this.gl.clearColor(0, 0, 0, 0);
+    this.gl.clear(this.gl.COLOR_BUFFER_BIT | this.gl.DEPTH_BUFFER_BIT);
+  }
+
+  public setSize(): boolean {
+    const realToCssPixels =
+      (this.enableHighDpiRendering ? window.devicePixelRatio : 1) * this.renderScale;
+
+    const canvasWidth = (this.gl.canvas as HTMLCanvasElement).clientWidth;
+    const canvasHeight = (this.gl.canvas as HTMLCanvasElement).clientHeight;
+
+    const displayWidth = Math.floor(canvasWidth * realToCssPixels);
+    const displayHeight = Math.floor(canvasHeight * realToCssPixels);
+
+    const oldSize = vec2.clone(this.getSize());
+    this.size = vec2.fromValues(displayWidth, displayHeight);
+
+    return this.size.x != oldSize.x || this.size.y != oldSize.y;
+  }
+
+  public getSize(): vec2 {
+    return this.size;
+  }
+}