egret-docs-master/Engine3D/Effect/Grass

• 草动画(GrassMesh)
  • 用来模拟实现风吹草动的效果；
  • 加入受角色对草产生的挤压效果；
  • 结合Egret3D的地形数据，可以通过Unity4导出场景中的草模型；
  • GrassMethod由GrassMesh自动生成，不建议您在外部创建这个对象。

---

module egret3d {
    export class Class_GrassMesh extends Class_View3D {

        protected view1: View3D;
        protected cameraCrl: LookAtController;

        private _grass: GrassMesh;
        private _lightFromBall: Mesh;
        private _lightVector: Vector3D;

        constructor() {
            super();
            this._egret3DCanvas.addEventListener(Event3D.ENTER_FRAME, this.update, this);

            this.view1 = new View3D(0, 0, window.innerWidth * window.devicePixelRatio, window.innerHeight * window.devicePixelRatio);

            this.view1.backColor = 0xff000000;
            this._egret3DCanvas.addView3D(this.view1);

            var bgImg: HTMLImageElement = <HTMLImageElement>document.getElementById("bg");
            var tex: ImageTexture = new ImageTexture(bgImg);

            this.cameraCrl = new LookAtController(this.view1.camera3D, new Object3D());
            this.cameraCrl.distance = 600;
            this.cameraCrl.rotationX = 60;


            this._lightFromBall = new Mesh(new SphereGeometry(20));
            this.view1.addChild3D(this._lightFromBall);

            this.initGrass();
        }


        private parseDistribution(image:ImageData): Vector3D[] {
            var width: number = image.width;
            var height: number = image.height;

            var color: number;
            var offset: number;
            var ratio: number = 1 / 16;
            var positions: Vector3D[] = [];

            for (var i: number = 0; i < width; i++) {
                for (var j: number = 0; j < height; j++) {
                    offset = i * width + j;
                    offset *= 4;
                    color = image.data[offset] * ratio;
                    color = Math.round(color);
                    if (color > 0) {
                        this.getPosition(i, j, color, positions);
                    }
                }
            }

            return positions;
        }


        private getPosition(i: number, j: number, count: number, positions: Vector3D[]): void {
            var pos: Vector3D;
            for (var i: number = 0; i < count; i++) {
                //随机一个值
                pos = new Vector3D(i, 0, j);
                positions.push(pos);
            }
        }

        private initGrass(): void {
            var positions: Vector3D[] = this.createPositions();

            var mat: TextureMaterial = new TextureMaterial();
            mat.ambientColor = 0xffffff;
            mat.blendMode = BlendMode.NORMAL;
            mat.cutAlpha = 0.4;

            var data: GrassData = new GrassData();
            data.minWidth = 30;
            data.maxWidth = 70;
            data.minHeight = 30;
            data.maxHeight = 70;
            data.noiseSpread = 1;
            data.billboard = false;
            data.healthyColor = "0x00ff00";
            data.dryColor = "0xff8000";

            this._grass = new GrassMesh(positions, mat, data);
            this._grass.y = 20;
            this.view1.addChild3D(this._grass);

            var loadtex: URLLoader = new URLLoader("resource/scene/plant/leaf.png");
            loadtex.addEventListener(LoaderEvent3D.LOADER_COMPLETE, this.onLoadTexture, this);
            loadtex["mat"] = mat;


        }


        private createPositions(): Vector3D[] {
            var plane: PlaneValueShape = new PlaneValueShape();
            plane.width = 1000;
            plane.height = 1000;
            var positions: Vector3D[] = plane.calculate(1000);

            return positions;
        }

        protected onLoadTexture(e: LoaderEvent3D) {
            e.loader["mat"].diffuseTexture = e.loader.data;
        }

        private anlge: number = 0;
        private dirLight: DirectLight;
        private position: Vector3D = new Vector3D();
        public update(e: Event3D) {
            this.cameraCrl.update();

            this.anlge += 0.01;
            this.position.setTo(Math.sin(this.anlge) * 300, 10, Math.cos(this.anlge) * 300);
            this._lightFromBall.position = this.position;
            if (this._grass) {
                this._grass.method.updateSqueezeData(this.position, true, 60, 1);
            }
        }

    }
} 

示例展示为草动画受小球的挤压影响效果

---

• Unity中导出草的步骤：

• 创建地形对象

• 使Terrain处于选中状态，点击草的图标，获得当前为刷草模式

• 点击Edit Details进入草动画详细编辑模式

• 点击Add Grass Texture获得新建一组草的动画

• 在弹开的编辑草详细内容界面中，编辑贴图，调整各个属性，完成后点击Add按钮，草动画详细信息确认成功

• 于场景中地形区域，按住鼠标不放松，然后滑动鼠标，开始执行刷草

• 编辑完毕后，使用Egret3D提供的场景导出插件，导出当前场景。

• 最后用Egret3D的UnitLoader加载这个场景，查看草的动画。