Babylon.js/src/States/alphaCullingState.ts

import { Nullable } from "../types";

/**
 * @hidden
 **/
export class _AlphaState {
    private _isAlphaBlendDirty = false;
    private _isBlendFunctionParametersDirty = false;
    private _isBlendEquationParametersDirty = false;
    private _isBlendConstantsDirty = false;
    private _alphaBlend = false;
    private _blendFunctionParameters = new Array<Nullable<number>>(4);
    private _blendEquationParameters = new Array<Nullable<number>>(2);
    private _blendConstants = new Array<Nullable<number>>(4);

    /**
     * Initializes the state.
     */
    public constructor() {
        this.reset();
    }

    public get isDirty(): boolean {
        return this._isAlphaBlendDirty || this._isBlendFunctionParametersDirty;
    }

    public get alphaBlend(): boolean {
        return this._alphaBlend;
    }

    public set alphaBlend(value: boolean) {
        if (this._alphaBlend === value) {
            return;
        }

        this._alphaBlend = value;
        this._isAlphaBlendDirty = true;
    }

    public setAlphaBlendConstants(r: number, g: number, b: number, a: number): void {
        if (
            this._blendConstants[0] === r &&
            this._blendConstants[1] === g &&
            this._blendConstants[2] === b &&
            this._blendConstants[3] === a
        ) {
            return;
        }

        this._blendConstants[0] = r;
        this._blendConstants[1] = g;
        this._blendConstants[2] = b;
        this._blendConstants[3] = a;

        this._isBlendConstantsDirty = true;
    }

    public setAlphaBlendFunctionParameters(value0: number, value1: number, value2: number, value3: number): void {
        if (
            this._blendFunctionParameters[0] === value0 &&
            this._blendFunctionParameters[1] === value1 &&
            this._blendFunctionParameters[2] === value2 &&
            this._blendFunctionParameters[3] === value3
        ) {
            return;
        }

        this._blendFunctionParameters[0] = value0;
        this._blendFunctionParameters[1] = value1;
        this._blendFunctionParameters[2] = value2;
        this._blendFunctionParameters[3] = value3;

        this._isBlendFunctionParametersDirty = true;
    }

    public setAlphaEquationParameters(rgb: number, alpha: number): void {
        if (
            this._blendEquationParameters[0] === rgb &&
            this._blendEquationParameters[1] === alpha
        ) {
            return;
        }

        this._blendEquationParameters[0] = rgb;
        this._blendEquationParameters[1] = alpha;

        this._isBlendEquationParametersDirty = true;
    }

    public reset() {
        this._alphaBlend = false;
        this._blendFunctionParameters[0] = null;
        this._blendFunctionParameters[1] = null;
        this._blendFunctionParameters[2] = null;
        this._blendFunctionParameters[3] = null;

        this._blendEquationParameters[0] = null;
        this._blendEquationParameters[1] = null;

        this._blendConstants[0] = null;
        this._blendConstants[1] = null;
        this._blendConstants[2] = null;
        this._blendConstants[3] = null;

        this._isAlphaBlendDirty = true;
        this._isBlendFunctionParametersDirty = false;
        this._isBlendEquationParametersDirty = false;
        this._isBlendConstantsDirty = false;
    }

    public apply(gl: WebGLRenderingContext) {

        if (!this.isDirty) {
            return;
        }

        // Alpha blend
        if (this._isAlphaBlendDirty) {
            if (this._alphaBlend) {
                gl.enable(gl.BLEND);
            } else {
                gl.disable(gl.BLEND);
            }

            this._isAlphaBlendDirty = false;
        }

        // Alpha function
        if (this._isBlendFunctionParametersDirty) {
            gl.blendFuncSeparate(<number>this._blendFunctionParameters[0], <number>this._blendFunctionParameters[1], <number>this._blendFunctionParameters[2], <number>this._blendFunctionParameters[3]);
            this._isBlendFunctionParametersDirty = false;
        }

        // Alpha equation
        if (this._isBlendEquationParametersDirty) {
            gl.blendEquationSeparate(this._blendEquationParameters[0]!, this._blendEquationParameters[1]!);
            this._isBlendEquationParametersDirty = false;
        }

        // Constants
        if (this._isBlendConstantsDirty) {
            gl.blendColor(<number>this._blendConstants[0], <number>this._blendConstants[1], <number>this._blendConstants[2], <number>this._blendConstants[3]);
            this._isBlendConstantsDirty = false;
        }
    }
}