Breakable.h
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上传日期:2022-01-07
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- /*
- * Copyright (c) 2008-2009 Erin Catto http://www.gphysics.com
- *
- * This software is provided 'as-is', without any express or implied
- * warranty. In no event will the authors be held liable for any damages
- * arising from the use of this software.
- * Permission is granted to anyone to use this software for any purpose,
- * including commercial applications, and to alter it and redistribute it
- * freely, subject to the following restrictions:
- * 1. The origin of this software must not be misrepresented; you must not
- * claim that you wrote the original software. If you use this software
- * in a product, an acknowledgment in the product documentation would be
- * appreciated but is not required.
- * 2. Altered source versions must be plainly marked as such, and must not be
- * misrepresented as being the original software.
- * 3. This notice may not be removed or altered from any source distribution.
- */
- #ifndef BREAKABLE_TEST_H
- #define BREAKABLE_TEST_H
- // This is used to test sensor shapes.
- class Breakable : public Test
- {
- public:
- enum
- {
- e_count = 7
- };
- Breakable()
- {
- // Ground body
- {
- b2BodyDef bd;
- b2Body* ground = m_world->CreateBody(&bd);
- b2PolygonShape shape;
- shape.SetAsEdge(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
- ground->CreateFixture(&shape, 0.0f);
- }
- // Breakable dynamic body
- {
- b2BodyDef bd;
- bd.type = b2_dynamicBody;
- bd.position.Set(0.0f, 40.0f);
- bd.angle = 0.25f * b2_pi;
- m_body1 = m_world->CreateBody(&bd);
- m_shape1.SetAsBox(0.5f, 0.5f, b2Vec2(-0.5f, 0.0f), 0.0f);
- m_piece1 = m_body1->CreateFixture(&m_shape1, 1.0f);
- m_shape2.SetAsBox(0.5f, 0.5f, b2Vec2(0.5f, 0.0f), 0.0f);
- m_piece2 = m_body1->CreateFixture(&m_shape2, 1.0f);
- }
- m_break = false;
- m_broke = false;
- }
- void PostSolve(b2Contact* contact, const b2ContactImpulse* impulse)
- {
- if (m_broke)
- {
- // The body already broke.
- return;
- }
- // Should the body break?
- int32 count = contact->GetManifold()->pointCount;
- float32 maxImpulse = 0.0f;
- for (int32 i = 0; i < count; ++i)
- {
- maxImpulse = b2Max(maxImpulse, impulse->normalImpulses[i]);
- }
- if (maxImpulse > 40.0f)
- {
- // Flag the body for breaking.
- m_break = true;
- }
- }
- void Break()
- {
- // Create two bodies from one.
- b2Body* body1 = m_piece1->GetBody();
- b2Vec2 center = body1->GetWorldCenter();
- body1->DestroyFixture(m_piece2);
- m_piece2 = NULL;
- b2BodyDef bd;
- bd.type = b2_dynamicBody;
- bd.position = body1->GetPosition();
- bd.angle = body1->GetAngle();
- b2Body* body2 = m_world->CreateBody(&bd);
- m_piece2 = body2->CreateFixture(&m_shape2, 1.0f);
- // Compute consistent velocities for new bodies based on
- // cached velocity.
- b2Vec2 center1 = body1->GetWorldCenter();
- b2Vec2 center2 = body2->GetWorldCenter();
-
- b2Vec2 velocity1 = m_velocity + b2Cross(m_angularVelocity, center1 - center);
- b2Vec2 velocity2 = m_velocity + b2Cross(m_angularVelocity, center2 - center);
- body1->SetAngularVelocity(m_angularVelocity);
- body1->SetLinearVelocity(velocity1);
- body2->SetAngularVelocity(m_angularVelocity);
- body2->SetLinearVelocity(velocity2);
- }
- void Step(Settings* settings)
- {
- if (m_break)
- {
- Break();
- m_broke = true;
- m_break = false;
- }
- // Cache velocities to improve movement on breakage.
- if (m_broke == false)
- {
- m_velocity = m_body1->GetLinearVelocity();
- m_angularVelocity = m_body1->GetAngularVelocity();
- }
- Test::Step(settings);
- }
- static Test* Create()
- {
- return new Breakable;
- }
- b2Body* m_body1;
- b2Vec2 m_velocity;
- float32 m_angularVelocity;
- b2PolygonShape m_shape1;
- b2PolygonShape m_shape2;
- b2Fixture* m_piece1;
- b2Fixture* m_piece2;
- bool m_broke;
- bool m_break;
- };
- #endif