From 74cbb4c9fde7a030720fd5609bb943be75572c37 Mon Sep 17 00:00:00 2001
From: yhh <359807859@qq.com>
Date: Wed, 10 Jun 2020 20:29:16 +0800
Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E5=A2=9Everletworld?=
MIME-Version: 1.0
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---
 .../src/Utils/Verlet/Composites/Composite.ts  | 25 +++++++++++
 .../src/Utils/Verlet/Constraint/Constraint.ts |  5 +++
 source/src/Utils/Verlet/Particle.ts           | 17 +++++++
 source/src/Utils/Verlet/VerletWorld.ts        | 45 +++++++++++++++++++
 4 files changed, 92 insertions(+)
 create mode 100644 source/src/Utils/Verlet/Composites/Composite.ts
 create mode 100644 source/src/Utils/Verlet/Constraint/Constraint.ts
 create mode 100644 source/src/Utils/Verlet/Particle.ts
 create mode 100644 source/src/Utils/Verlet/VerletWorld.ts

diff --git a/source/src/Utils/Verlet/Composites/Composite.ts b/source/src/Utils/Verlet/Composites/Composite.ts
new file mode 100644
index 00000000..f3caeada
--- /dev/null
+++ b/source/src/Utils/Verlet/Composites/Composite.ts
@@ -0,0 +1,25 @@
+class Composite {
+    private _constraints: Constraint[] = [];
+
+    public particles: Particle[] = [];
+    /**
+     * 处理解决所有约束条件
+     */
+    public solveConstraints(){
+        for (let i = this._constraints.length - 1; i >= 0; i --){
+            this._constraints[i].solve();
+        }
+    }
+
+    public updateParticles(deltaTimeSquared: number, gravity: Vector2){
+        for (let j = 0; j < this.particles.length; j ++){
+            let p = this.particles[j];
+            if (p.isPinned){
+                p.position = p.pinnedPosition;
+                continue;
+            }
+
+            p.applyForce(Vector2.multiply(new Vector2(p.mass, p.mass), gravity));
+        }
+    }
+}
\ No newline at end of file
diff --git a/source/src/Utils/Verlet/Constraint/Constraint.ts b/source/src/Utils/Verlet/Constraint/Constraint.ts
new file mode 100644
index 00000000..e371f532
--- /dev/null
+++ b/source/src/Utils/Verlet/Constraint/Constraint.ts
@@ -0,0 +1,5 @@
+abstract class Constraint {
+    public composite: Composite;
+
+    public abstract solve();
+}
\ No newline at end of file
diff --git a/source/src/Utils/Verlet/Particle.ts b/source/src/Utils/Verlet/Particle.ts
new file mode 100644
index 00000000..511a713d
--- /dev/null
+++ b/source/src/Utils/Verlet/Particle.ts
@@ -0,0 +1,17 @@
+class Particle {
+    public position: Vector2;
+    public lastPosition: Vector2;
+    public isPinned: boolean;
+    public pinnedPosition;
+    public acceleration: Vector2;
+    public mass: number = 1;
+
+    constructor(position: Vector2){
+        this.position = position;
+        this.lastPosition = position;
+    }
+
+    public applyForce(force: Vector2){
+        this.acceleration = Vector2.add(this.acceleration, new Vector2(force.x / this.mass, force.y / this.mass));
+    }
+}
\ No newline at end of file
diff --git a/source/src/Utils/Verlet/VerletWorld.ts b/source/src/Utils/Verlet/VerletWorld.ts
new file mode 100644
index 00000000..f2be8ff2
--- /dev/null
+++ b/source/src/Utils/Verlet/VerletWorld.ts
@@ -0,0 +1,45 @@
+/**
+ * 基于verlet 物理引擎进行改造的物理引擎 ts重写
+ * https://github.com/subprotocol/verlet-js
+ */
+class VerletWorld {
+    public gravity: Vector2 = new Vector2(0, 980);
+    public maximumStepIterations = 5;
+    public constraintIterations = 3;
+    public simulationBounds: Rectangle;
+
+    private _leftOverTime: number;
+    private _iterationSteps: number;
+    private _fixedDeltaTime = 1 / 60;
+    private _composites: Composite[] = [];
+    private _fixedDeltaTimeSq: number;
+
+    constructor(simulationBounds?: Rectangle){
+        this.simulationBounds = simulationBounds;
+        this._fixedDeltaTimeSq = Math.pow(this._fixedDeltaTime, 2);
+    }
+
+    public update(){
+        this.updateTiming();
+
+        for (let iteration = 1; iteration <= this._iterationSteps; iteration ++){
+            for (let i = this._composites.length - 1; i >= 0; i --){
+                let composite = this._composites[i];
+
+                for (let s = 0; s < this.constraintIterations; s++){
+                    composite.solveConstraints();
+                }
+
+                composite.updateParticles(this._fixedDeltaTimeSq, this.gravity);
+            }
+        }
+    }
+
+    private updateTiming(){
+        this._leftOverTime += Time.deltaTime;
+        this._iterationSteps = Math.trunc(this._leftOverTime / this._fixedDeltaTime);
+        this._leftOverTime -= this._iterationSteps * this._fixedDeltaTime;
+
+        this._iterationSteps = Math.min(this._iterationSteps, this.maximumStepIterations);
+    }
+}
\ No newline at end of file