JUCE/examples/Demo/Source/Demos/Box2DTests/RayCast.h

/*
* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
*
* 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 RAY_CAST_H
#define RAY_CAST_H

// This test demonstrates how to use the world ray-cast feature.
// NOTE: we are intentionally filtering one of the polygons, therefore
// the ray will always miss one type of polygon.

// This callback finds the closest hit. Polygon 0 is filtered.
class RayCastClosestCallback : public b2RayCastCallback
{
public:
    RayCastClosestCallback()
    {
        m_hit = false;
    }

    float32 ReportFixture(  b2Fixture* fixture, const b2Vec2& point,
        const b2Vec2& normal, float32 fraction)
    {
        b2Body* body = fixture->GetBody();
        void* userData = body->GetUserData();
        if (userData)
        {
            int32 index = *(int32*)userData;
            if (index == 0)
            {
                // filter
                return -1.0f;
            }
        }

        m_hit = true;
        m_point = point;
        m_normal = normal;
        return fraction;
    }

    bool m_hit;
    b2Vec2 m_point;
    b2Vec2 m_normal;
};

// This callback finds any hit. Polygon 0 is filtered.
class RayCastAnyCallback : public b2RayCastCallback
{
public:
    RayCastAnyCallback()
    {
        m_hit = false;
    }

    float32 ReportFixture(  b2Fixture* fixture, const b2Vec2& point,
        const b2Vec2& normal, float32 fraction)
    {
        b2Body* body = fixture->GetBody();
        void* userData = body->GetUserData();
        if (userData)
        {
            int32 index = *(int32*)userData;
            if (index == 0)
            {
                // filter
                return -1.0f;
            }
        }

        m_hit = true;
        m_point = point;
        m_normal = normal;
        return 0.0f;
    }

    bool m_hit;
    b2Vec2 m_point;
    b2Vec2 m_normal;
};

// This ray cast collects multiple hits along the ray. Polygon 0 is filtered.
class RayCastMultipleCallback : public b2RayCastCallback
{
public:
    enum
    {
        e_maxCount = 3
    };

    RayCastMultipleCallback()
    {
        m_count = 0;
    }

    float32 ReportFixture(  b2Fixture* fixture, const b2Vec2& point,
        const b2Vec2& normal, float32 fraction)
    {
        b2Body* body = fixture->GetBody();
        void* userData = body->GetUserData();
        if (userData)
        {
            int32 index = *(int32*)userData;
            if (index == 0)
            {
                // filter
                return -1.0f;
            }
        }

        b2Assert(m_count < e_maxCount);

        m_points[m_count] = point;
        m_normals[m_count] = normal;
        ++m_count;

        if (m_count == e_maxCount)
        {
            return 0.0f;
        }

        return 1.0f;
    }

    b2Vec2 m_points[e_maxCount];
    b2Vec2 m_normals[e_maxCount];
    int32 m_count;
};


class RayCast : public Test
{
public:

    enum
    {
        e_maxBodies = 256
    };

    enum Mode
    {
        e_closest,
        e_any,
        e_multiple
    };

    RayCast()
    {
        // Ground body
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            b2EdgeShape shape;
            shape.Set(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
            ground->CreateFixture(&shape, 0.0f);
        }

        {
            b2Vec2 vertices[3];
            vertices[0].Set(-0.5f, 0.0f);
            vertices[1].Set(0.5f, 0.0f);
            vertices[2].Set(0.0f, 1.5f);
            m_polygons[0].Set(vertices, 3);
        }

        {
            b2Vec2 vertices[3];
            vertices[0].Set(-0.1f, 0.0f);
            vertices[1].Set(0.1f, 0.0f);
            vertices[2].Set(0.0f, 1.5f);
            m_polygons[1].Set(vertices, 3);
        }

        {
            float32 w = 1.0f;
            float32 b = w / (2.0f + b2Sqrt(2.0f));
            float32 s = b2Sqrt(2.0f) * b;

            b2Vec2 vertices[8];
            vertices[0].Set(0.5f * s, 0.0f);
            vertices[1].Set(0.5f * w, b);
            vertices[2].Set(0.5f * w, b + s);
            vertices[3].Set(0.5f * s, w);
            vertices[4].Set(-0.5f * s, w);
            vertices[5].Set(-0.5f * w, b + s);
            vertices[6].Set(-0.5f * w, b);
            vertices[7].Set(-0.5f * s, 0.0f);

            m_polygons[2].Set(vertices, 8);
        }

        {
            m_polygons[3].SetAsBox(0.5f, 0.5f);
        }

        {
            m_circle.m_radius = 0.5f;
        }

        m_bodyIndex = 0;
        memset(m_bodies, 0, sizeof(m_bodies));

        m_angle = 0.0f;

        m_mode = e_closest;
    }

    void Create(int32 index)
    {
        if (m_bodies[m_bodyIndex] != NULL)
        {
            m_world->DestroyBody(m_bodies[m_bodyIndex]);
            m_bodies[m_bodyIndex] = NULL;
        }

        b2BodyDef bd;

        float32 x = RandomFloat(-10.0f, 10.0f);
        float32 y = RandomFloat(0.0f, 20.0f);
        bd.position.Set(x, y);
        bd.angle = RandomFloat(-b2_pi, b2_pi);

        m_userData[m_bodyIndex] = index;
        bd.userData = m_userData + m_bodyIndex;

        if (index == 4)
        {
            bd.angularDamping = 0.02f;
        }

        m_bodies[m_bodyIndex] = m_world->CreateBody(&bd);

        if (index < 4)
        {
            b2FixtureDef fd;
            fd.shape = m_polygons + index;
            fd.friction = 0.3f;
            m_bodies[m_bodyIndex]->CreateFixture(&fd);
        }
        else
        {
            b2FixtureDef fd;
            fd.shape = &m_circle;
            fd.friction = 0.3f;

            m_bodies[m_bodyIndex]->CreateFixture(&fd);
        }

        m_bodyIndex = (m_bodyIndex + 1) % e_maxBodies;
    }

    void DestroyBody()
    {
        for (int32 i = 0; i < e_maxBodies; ++i)
        {
            if (m_bodies[i] != NULL)
            {
                m_world->DestroyBody(m_bodies[i]);
                m_bodies[i] = NULL;
                return;
            }
        }
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
            Create(key - '1');
            break;

        case 'd':
            DestroyBody();
            break;

        case 'm':
            if (m_mode == e_closest)
            {
                m_mode = e_any;
            }
            else if (m_mode == e_any)
            {
                m_mode = e_multiple;
            }
            else if (m_mode == e_multiple)
            {
                m_mode = e_closest;
            }
        }
    }

    void Step(Settings* settings)
    {
        bool advanceRay = settings->pause == 0 || settings->singleStep;

        Test::Step(settings);
        m_debugDraw.DrawString(5, m_textLine, "Press 1-5 to drop stuff, m to change the mode");
        m_textLine += 15;
        m_debugDraw.DrawString(5, m_textLine, "Mode = %d", m_mode);
        m_textLine += 15;

        float32 L = 11.0f;
        b2Vec2 point1(0.0f, 10.0f);
        b2Vec2 d(L * cosf(m_angle), L * sinf(m_angle));
        b2Vec2 point2 = point1 + d;

        if (m_mode == e_closest)
        {
            RayCastClosestCallback callback;
            m_world->RayCast(&callback, point1, point2);

            if (callback.m_hit)
            {
                m_debugDraw.DrawPoint(callback.m_point, 5.0f, b2Color(0.4f, 0.9f, 0.4f));
                m_debugDraw.DrawSegment(point1, callback.m_point, b2Color(0.8f, 0.8f, 0.8f));
                b2Vec2 head = callback.m_point + 0.5f * callback.m_normal;
                m_debugDraw.DrawSegment(callback.m_point, head, b2Color(0.9f, 0.9f, 0.4f));
            }
            else
            {
                m_debugDraw.DrawSegment(point1, point2, b2Color(0.8f, 0.8f, 0.8f));
            }
        }
        else if (m_mode == e_any)
        {
            RayCastAnyCallback callback;
            m_world->RayCast(&callback, point1, point2);

            if (callback.m_hit)
            {
                m_debugDraw.DrawPoint(callback.m_point, 5.0f, b2Color(0.4f, 0.9f, 0.4f));
                m_debugDraw.DrawSegment(point1, callback.m_point, b2Color(0.8f, 0.8f, 0.8f));
                b2Vec2 head = callback.m_point + 0.5f * callback.m_normal;
                m_debugDraw.DrawSegment(callback.m_point, head, b2Color(0.9f, 0.9f, 0.4f));
            }
            else
            {
                m_debugDraw.DrawSegment(point1, point2, b2Color(0.8f, 0.8f, 0.8f));
            }
        }
        else if (m_mode == e_multiple)
        {
            RayCastMultipleCallback callback;
            m_world->RayCast(&callback, point1, point2);
            m_debugDraw.DrawSegment(point1, point2, b2Color(0.8f, 0.8f, 0.8f));

            for (int32 i = 0; i < callback.m_count; ++i)
            {
                b2Vec2 p = callback.m_points[i];
                b2Vec2 n = callback.m_normals[i];
                m_debugDraw.DrawPoint(p, 5.0f, b2Color(0.4f, 0.9f, 0.4f));
                m_debugDraw.DrawSegment(point1, p, b2Color(0.8f, 0.8f, 0.8f));
                b2Vec2 head = p + 0.5f * n;
                m_debugDraw.DrawSegment(p, head, b2Color(0.9f, 0.9f, 0.4f));
            }
        }

        if (advanceRay)
        {
            m_angle += 0.25f * b2_pi / 180.0f;
        }

#if 0
        // This case was failing.
        {
            b2Vec2 vertices[4];
            //vertices[0].Set(-22.875f, -3.0f);
            //vertices[1].Set(22.875f, -3.0f);
            //vertices[2].Set(22.875f, 3.0f);
            //vertices[3].Set(-22.875f, 3.0f);

            b2PolygonShape shape;
            //shape.Set(vertices, 4);
            shape.SetAsBox(22.875f, 3.0f);

            b2RayCastInput input;
            input.p1.Set(10.2725f,1.71372f);
            input.p2.Set(10.2353f,2.21807f);
            //input.maxFraction = 0.567623f;
            input.maxFraction = 0.56762173f;

            b2Transform xf;
            xf.SetIdentity();
            xf.position.Set(23.0f, 5.0f);

            b2RayCastOutput output;
            bool hit;
            hit = shape.RayCast(&output, input, xf);
            hit = false;

            b2Color color(1.0f, 1.0f, 1.0f);
            b2Vec2 vs[4];
            for (int32 i = 0; i < 4; ++i)
            {
                vs[i] = b2Mul(xf, shape.m_vertices[i]);
            }

            m_debugDraw.DrawPolygon(vs, 4, color);
            m_debugDraw.DrawSegment(input.p1, input.p2, color);
        }
#endif
    }

    static Test* Create()
    {
        return new RayCast;
    }

    int32 m_bodyIndex;
    b2Body* m_bodies[e_maxBodies];
    int32 m_userData[e_maxBodies];
    b2PolygonShape m_polygons[4];
    b2CircleShape m_circle;

    float32 m_angle;

    Mode m_mode;
};

#endif