Initial

resources/app/client/pixi/webgl/helpers/framebuffer-snapshot.js

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+/**
+ * Provide the necessary methods to get a snapshot of the framebuffer into a render texture.
+ * Class meant to be used as a singleton.
+ * Created with the precious advices of dev7355608.
+ */
+class FramebufferSnapshot {
+  constructor() {
+    /**
+     * The RenderTexture that is the render destination for the framebuffer snapshot.
+     * @type {PIXI.RenderTexture}
+     */
+    this.framebufferTexture = FramebufferSnapshot.#createRenderTexture();
+
+    // Listen for resize events
+    canvas.app.renderer.on("resize", () => this.#hasResized = true);
+  }
+
+  /**
+   * To know if we need to update the texture.
+   * @type {boolean}
+   */
+  #hasResized = true;
+
+  /**
+   * A placeholder for temporary copy.
+   * @type {PIXI.Rectangle}
+   */
+  #tempSourceFrame = new PIXI.Rectangle();
+
+  /* ---------------------------------------- */
+
+  /**
+   * Get the framebuffer texture snapshot.
+   * @param {PIXI.Renderer} renderer    The renderer for this context.
+   * @returns {PIXI.RenderTexture}      The framebuffer snapshot.
+   */
+  getFramebufferTexture(renderer) {
+    // Need resize?
+    if ( this.#hasResized ) {
+      CachedContainer.resizeRenderTexture(renderer, this.framebufferTexture);
+      this.#hasResized = false;
+    }
+
+    // Flush batched operations before anything else
+    renderer.batch.flush();
+
+    const fb = renderer.framebuffer.current;
+    const vf = this.#tempSourceFrame.copyFrom(renderer.renderTexture.viewportFrame);
+
+    // Inverted Y in the case of canvas
+    if ( !fb ) vf.y = renderer.view.height - (vf.y + vf.height);
+
+    // Empty viewport
+    if ( !(vf.width > 0 && vf.height > 0) ) return PIXI.Texture.WHITE;
+
+    // Computing bounds of the source
+    let srcX = vf.x;
+    let srcY = vf.y;
+    let srcX2 = srcX + vf.width;
+    let srcY2 = srcY + vf.height;
+
+    // Inverted Y in the case of canvas
+    if ( !fb ) {
+      srcY = renderer.view.height - 1 - srcY;
+      srcY2 = srcY - vf.height;
+    }
+
+    // Computing bounds of the destination
+    let dstX = 0;
+    let dstY = 0;
+    let dstX2 = vf.width;
+    let dstY2 = vf.height;
+
+    // Preparing the gl context
+    const gl = renderer.gl;
+    const framebufferSys = renderer.framebuffer;
+    const currentFramebuffer = framebufferSys.current;
+
+    // Binding our render texture to the framebuffer
+    framebufferSys.bind(this.framebufferTexture.framebuffer, framebufferSys.viewport);
+    // Current framebuffer is binded as a read framebuffer (to prepare the blit)
+    gl.bindFramebuffer(gl.READ_FRAMEBUFFER, fb?.glFramebuffers[framebufferSys.CONTEXT_UID].framebuffer);
+    // Blit current framebuffer into our render texture
+    gl.blitFramebuffer(srcX, srcY, srcX2, srcY2, dstX, dstY, dstX2, dstY2, gl.COLOR_BUFFER_BIT, gl.NEAREST);
+    // Restore original behavior
+    framebufferSys.bind(currentFramebuffer, framebufferSys.viewport);
+
+    return this.framebufferTexture;
+  }
+
+  /* ---------------------------------------- */
+
+  /**
+   * Create a render texture, provide a render method and an optional clear color.
+   * @returns {PIXI.RenderTexture}              A reference to the created render texture.
+   */
+  static #createRenderTexture() {
+    const renderer = canvas.app?.renderer;
+    return PIXI.RenderTexture.create({
+      width: renderer?.screen.width ?? window.innerWidth,
+      height: renderer?.screen.height ?? window.innerHeight,
+      resolution: renderer.resolution ?? PIXI.settings.RESOLUTION
+    });
+  }
+}