Method begin

src/webgl/p5.Framebuffer.js:763–787

* Begins drawing shapes to the framebuffer. * * `myBuffer.begin()` and myBuffer.end() * allow shapes to be drawn to the framebuffer. `myBuffer.begin()` begins * drawing to the framebuffer and * myBuffer.end() stops

()

   * }
   */
  begin() {
    this.prevFramebuffer = this.renderer.activeFramebuffer();
    if (this.prevFramebuffer) {
      this.prevFramebuffer._beforeEnd();
    }
    this.renderer.activeFramebuffers.push(this);
    this._beforeBegin();
    this.renderer.push();
    // Apply the framebuffer's camera. This does almost what
    // RendererGL.reset() does, but this does not try to clear any buffers;
    // it only sets the camera.
    // this.renderer.setCamera(this.defaultCamera);
    this.renderer.states.setValue('curCamera', this.defaultCamera);
    // set the projection matrix (which is not normally updated each frame)
    this.renderer.states.setValue('uPMatrix', this.renderer.states.uPMatrix.clone());
    this.renderer.states.uPMatrix.set(this.defaultCamera.projMatrix);
    this.renderer.states.setValue('uViewMatrix', this.renderer.states.uViewMatrix.clone());
    this.renderer.states.uViewMatrix.set(this.defaultCamera.cameraMatrix);

    this.renderer.resetMatrix();
    this.renderer.states.uViewMatrix
      .set(this.renderer.states.curCamera.cameraMatrix);
    this.renderer.states.uModelMatrix.reset();
    this.renderer._applyStencilTestIfClipping();
  }

  /**
   * When making a p5.Framebuffer active so that it may be drawn to, this method