add expressions

cocos/vfx/expression.ts

@@ -22,11 +22,12 @@
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  */
-import { ParticleEmitterParams, ParticleExecContext } from "./particle-base";
-import { ParticleDataSet } from "./particle-data-set";
+import { ccclass } from '../core/data/decorators';
+import { ParticleEmitterParams, ParticleExecContext } from './particle-base';
+import { ParticleDataSet } from './particle-data-set';
 
+@ccclass('cc.Expression')
 export abstract class Expression {
     public abstract tick (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext);
-    public abstract bind (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext);
-    public abstract evaluate (index: number);
-}
+    public abstract bind (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext, randomOffset: number);
+}

cocos/vfx/expressions/constant-vec3.ts

@@ -0,0 +1,45 @@
+import { CCFloat, Vec3, serializable } from '../../core';
+import { ccclass, type } from '../../core/data/class-decorator';
+import { ParticleEmitterParams, ParticleExecContext } from '../particle-base';
+import { ParticleDataSet } from '../particle-data-set';
+import { RandomStream } from '../random-stream';
+import { Vec3Expression } from './vec3';
+
+@ccclass('cc.ConstantVec3')
+export class ConstantVec3Expression extends Vec3Expression {
+    @type(CCFloat)
+    @serializable
+    public x = 0;
+
+    @type(CCFloat)
+    @serializable
+    public y = 0;
+
+    @type(CCFloat)
+    @serializable
+    public z = 0;
+
+    constructor (val: Vec3 = Vec3.ZERO) {
+        super();
+        this.x = val.x;
+        this.y = val.y;
+        this.z = val.z;
+    }
+
+    public tick (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext) {}
+    public bind (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext, randomOffset: number) {}
+
+    public evaluate (index: number, out: Vec3) {
+        out.x = this.x;
+        out.y = this.y;
+        out.z = this.z;
+        return out;
+    }
+
+    public evaluateSingle (time: number, randomStream: RandomStream, context: ParticleExecContext, out: Vec3) {
+        out.x = this.x;
+        out.y = this.y;
+        out.z = this.z;
+        return out;
+    }
+}

cocos/vfx/expressions/constant.ts

@@ -0,0 +1,53 @@
+/*
+ Copyright (c) 2020 Xiamen Yaji Software Co., Ltd.
+
+ https://www.cocos.com/
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated engine source code (the "Software"), a limited,
+ worldwide, royalty-free, non-assignable, revocable and non-exclusive license
+ to use Cocos Creator solely to develop games on your target platforms. You shall
+ not use Cocos Creator software for developing other software or tools that's
+ used for developing games. You are not granted to publish, distribute,
+ sublicense, and/or sell copies of Cocos Creator.
+
+ The software or tools in this License Agreement are licensed, not sold.
+ Xiamen Yaji Software Co., Ltd. reserves all rights not expressly granted to you.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+ */
+import { CCFloat } from '../../core';
+import { ccclass, serializable, type } from '../../core/data/class-decorator';
+import { ParticleEmitterParams, ParticleExecContext } from '../particle-base';
+import { ParticleDataSet } from '../particle-data-set';
+import { RandomStream } from '../random-stream';
+import { FloatExpression } from './float';
+
+@ccclass('cc.ConstantExpression')
+export class ConstantExpression extends FloatExpression {
+    @type(CCFloat)
+    @serializable
+    public value = 0;
+
+    constructor (value = 0) {
+        super();
+        this.value = value;
+    }
+
+    public tick (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext) {}
+    public bind (particles: ParticleDataSet, params: ParticleEmitterParams, context: ParticleExecContext, randomOffset: number) {}
+
+    public evaluate (index: number): number {
+        return this.value;
+    }
+
+    public evaluateSingle (time: number, randomStream: RandomStream, context: ParticleExecContext): number {
+        return this.value;
+    }
+}