import { AbstractMaskSystem } from './AbstractMaskSystem';
import type { Renderer } from '../Renderer';
import type { IMaskTarget, MaskData } from './MaskData';
/**
* System plugin to the renderer to manage stencils (used for masks).
*
* @class
* @extends PIXI.System
* @memberof PIXI
*/
export class StencilSystem extends AbstractMaskSystem
{
/**
* @param {PIXI.Renderer} renderer - The renderer this System works for.
*/
constructor(renderer: Renderer)
{
super(renderer);
this.glConst = WebGLRenderingContext.STENCIL_TEST;
}
getStackLength(): number
{
const maskData = this.maskStack[this.maskStack.length - 1];
if (maskData)
{
return maskData._stencilCounter;
}
return 0;
}
/**
* Applies the Mask and adds it to the current stencil stack.
*
* @param {PIXI.MaskData} maskData - The mask data
*/
push(maskData: MaskData): void
{
const maskObject = maskData.maskObject;
const { gl } = this.renderer;
const prevMaskCount = maskData._stencilCounter;
if (prevMaskCount === 0)
{
// force use stencil texture in current framebuffer
this.renderer.framebuffer.forceStencil();
gl.enable(gl.STENCIL_TEST);
}
maskData._stencilCounter++;
// Increment the reference stencil value where the new mask overlaps with the old ones.
gl.colorMask(false, false, false, false);
gl.stencilFunc(gl.EQUAL, prevMaskCount, this._getBitwiseMask());
gl.stencilOp(gl.KEEP, gl.KEEP, gl.INCR);
maskObject.renderable = true;
maskObject.render(this.renderer);
this.renderer.batch.flush();
this.renderer.framebuffer.blit();
maskObject.renderable = false;
this._useCurrent();
}
/**
* Pops stencil mask. MaskData is already removed from stack
*
* @param {PIXI.DisplayObject} maskObject - object of popped mask data
*/
pop(maskObject: IMaskTarget): void
{
const gl = this.renderer.gl;
if (this.getStackLength() === 0)
{
// the stack is empty!
gl.disable(gl.STENCIL_TEST);
gl.clear(gl.STENCIL_BUFFER_BIT);
gl.clearStencil(0);
}
else
{
// Decrement the reference stencil value where the popped mask overlaps with the other ones
gl.colorMask(false, false, false, false);
gl.stencilOp(gl.KEEP, gl.KEEP, gl.DECR);
maskObject.renderable = true;
maskObject.render(this.renderer);
this.renderer.batch.flush();
maskObject.renderable = false;
this._useCurrent();
}
}
/**
* Setup renderer to use the current stencil data.
* @private
*/
_useCurrent(): void
{
const gl = this.renderer.gl;
gl.colorMask(true, true, true, true);
gl.stencilFunc(gl.EQUAL, this.getStackLength(), this._getBitwiseMask());
gl.stencilOp(gl.KEEP, gl.KEEP, gl.KEEP);
}
/**
* Fill 1s equal to the number of acitve stencil masks.
* @private
* @return {number} The bitwise mask.
*/
_getBitwiseMask(): number
{
return (1 << this.getStackLength()) - 1;
}
}