Add initial prototype.

3-mid/physics/implement/box2d/contrib/testbed/tests/pulley_joint.cpp

@@ -0,0 +1,96 @@
+// MIT License
+
+// Copyright (c) 2019 Erin Catto
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// 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.
+
+#include "test.h"
+
+class PulleyJoint : public Test
+{
+public:
+	PulleyJoint()
+	{
+		float y = 16.0f;
+		float L = 12.0f;
+		float a = 1.0f;
+		float b = 2.0f;
+
+		b2Body* ground = NULL;
+		{
+			b2BodyDef bd;
+			ground = m_world->CreateBody(&bd);
+
+			b2CircleShape circle;
+			circle.m_radius = 2.0f;
+
+			circle.m_p.Set(-10.0f, y + b + L);
+			ground->CreateFixture(&circle, 0.0f);
+
+			circle.m_p.Set(10.0f, y + b + L);
+			ground->CreateFixture(&circle, 0.0f);
+		}
+
+		{
+
+			b2PolygonShape shape;
+			shape.SetAsBox(a, b);
+
+			b2BodyDef bd;
+			bd.type = b2_dynamicBody;
+
+			//bd.fixedRotation = true;
+			bd.position.Set(-10.0f, y);
+			b2Body* body1 = m_world->CreateBody(&bd);
+			body1->CreateFixture(&shape, 5.0f);
+
+			bd.position.Set(10.0f, y);
+			b2Body* body2 = m_world->CreateBody(&bd);
+			body2->CreateFixture(&shape, 5.0f);
+
+			b2PulleyJointDef pulleyDef;
+			b2Vec2 anchor1(-10.0f, y + b);
+			b2Vec2 anchor2(10.0f, y + b);
+			b2Vec2 groundAnchor1(-10.0f, y + b + L);
+			b2Vec2 groundAnchor2(10.0f, y + b + L);
+			pulleyDef.Initialize(body1, body2, groundAnchor1, groundAnchor2, anchor1, anchor2, 1.5f);
+
+			m_joint1 = (b2PulleyJoint*)m_world->CreateJoint(&pulleyDef);
+		}
+	}
+
+	void Step(Settings& settings) override
+	{
+		Test::Step(settings);
+
+		float ratio = m_joint1->GetRatio();
+		float L = m_joint1->GetCurrentLengthA() + ratio * m_joint1->GetCurrentLengthB();
+		g_debugDraw.DrawString(5, m_textLine, "L1 + %4.2f * L2 = %4.2f", (float) ratio, (float) L);
+		m_textLine += m_textIncrement;
+	}
+
+	static Test* Create()
+	{
+		return new PulleyJoint;
+	}
+
+	b2PulleyJoint* m_joint1;
+};
+
+static int testIndex = RegisterTest("Joints", "Pulley", PulleyJoint::Create);