/********************************************************************************
* ReactPhysics3D physics library, http://www.reactphysics3d.com                 *
* Copyright (c) 2010-2016 Daniel Chappuis                                       *
*********************************************************************************
*                                                                               *
* 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 HEIGHT_FIELD_H
#define HEIGHT_FIELD_H

// Libraries
#include "openglframework.h"
#include "reactphysics3d.h"
#include "PhysicsObject.h"


// Class HeightField
class HeightField : public PhysicsObject {

    private :

        static const int NB_POINTS_WIDTH = 100;
        static const int NB_POINTS_LENGTH = 100;

        // -------------------- Attributes -------------------- //

        /// Height field data
        float mHeightData[NB_POINTS_WIDTH * NB_POINTS_LENGTH];

        /// Previous transform (for interpolation)
        rp3d::Transform mPreviousTransform;

        /// Collision shape
        rp3d::HeightFieldShape* mHeightFieldShape;
        rp3d::ProxyShape* mProxyShape;

        /// Scaling matrix
        openglframework::Matrix4 mScalingMatrix;

        /// Vertex Buffer Object for the vertices data
        openglframework::VertexBufferObject mVBOVertices;

        /// Vertex Buffer Object for the normals data
        openglframework::VertexBufferObject mVBONormals;

        /// Vertex Buffer Object for the texture coords
        openglframework::VertexBufferObject mVBOTextureCoords;

        /// Vertex Buffer Object for the indices
        openglframework::VertexBufferObject mVBOIndices;

        /// Vertex Array Object for the vertex data
        openglframework::VertexArrayObject mVAO;

        /// Min/Max height of the height field values
        float mMinHeight, mMaxHeight;

        // -------------------- Methods -------------------- //

        /// Create the Vertex Buffer Objects used to render with OpenGL.
        void createVBOAndVAO();

        /// Compute the heights of the height field
        void generateHeightField();

        /// Generate the graphics mesh to render the height field
        void generateGraphicsMesh();

    public :

        // -------------------- Methods -------------------- //

        /// Constructor
        HeightField(reactphysics3d::PhysicsCommon& physicsCommon, rp3d::CollisionWorld* world);

        /// Constructor
        HeightField(float mass, rp3d::PhysicsCommon& physicsCommon, rp3d::DynamicsWorld* dynamicsWorld);

        /// Destructor
        ~HeightField();

        /// Render the mesh at the correct position and with the correct orientation
        void render(openglframework::Shader& shader,
                    const openglframework::Matrix4& worldToCameraMatrix) override;

        /// Update the transform matrix of the object
        virtual void updateTransform(float interpolationFactor) override;
};

// Update the transform matrix of the object
inline void HeightField::updateTransform(float interpolationFactor) {
    mTransformMatrix = computeTransform(interpolationFactor, mScalingMatrix);
}

#endif