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// 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"
// 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);
b2EdgeShape shape;
shape.SetTwoSided(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) override
{
if (m_broke)
{
// The body already broke.
return;
}
// Should the body break?
int32 count = contact->GetManifold()->pointCount;
float 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) override
{
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;
float m_angularVelocity;
b2PolygonShape m_shape1;
b2PolygonShape m_shape2;
b2Fixture* m_piece1;
b2Fixture* m_piece2;
bool m_broke;
bool m_break;
};
static int testIndex = RegisterTest("Examples", "Breakable", Breakable::Create);
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