RenderableObject.h

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/* Copyright (C) 2012 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Base class for renderable objects
 */

#ifndef INCLUDED_RENDERABLEOBJECT
#define INCLUDED_RENDERABLEOBJECT


#include "maths/BoundingBoxAligned.h"
#include "maths/Matrix3D.h"


// dirty flags - used as notification to the renderer that some bit of data
// need updating
#define RENDERDATA_UPDATE_VERTICES      (1<<1)
#define RENDERDATA_UPDATE_INDICES       (1<<2)
#define RENDERDATA_UPDATE_COLOR         (1<<4)


///////////////////////////////////////////////////////////////////////////////
// CRenderData: base class of all the renderer's renderdata classes - the
// derived class stores necessary information for rendering an object of a
// particular type
class CRenderData
{
public:
    CRenderData() : m_UpdateFlags(0) {}
    virtual ~CRenderData() {}

    int m_UpdateFlags;
};

///////////////////////////////////////////////////////////////////////////////
// CRenderableObject: base class of all renderable objects - patches, models,
// sprites, etc; stores position and bound information, and a pointer to
// some renderdata necessary for the renderer to actually render it
class CRenderableObject
{
    NONCOPYABLE(CRenderableObject);

public:
    // constructor
    CRenderableObject() : m_RenderData(0), m_BoundsValid(false)
    {
        m_Transform.SetIdentity();
    }
    // destructor
    virtual ~CRenderableObject() { delete m_RenderData; }

    // set object transform
    virtual void SetTransform(const CMatrix3D& transform)
    {
        if (m_Transform == transform)
            return;
        // store transform, calculate inverse
        m_Transform=transform;
        m_Transform.GetInverse(m_InvTransform);
        // normal recalculation likely required on transform change; flag it
        SetDirty(RENDERDATA_UPDATE_VERTICES);
        // need to rebuild world space bounds
        InvalidateBounds();
    }
    // get object to world space transform
    const CMatrix3D& GetTransform() const { return m_Transform; }
    // get world to object space transform
    const CMatrix3D& GetInvTransform() const { return m_InvTransform; }

    // mark some part of the renderdata as dirty, and requiring
    // an update on next render
    void SetDirty(u32 dirtyflags)
    {
        if (m_RenderData)
            m_RenderData->m_UpdateFlags |= dirtyflags;
    }

    /**
     * (Re)calculates and stores any bounds or bound-dependent data for this object. At this abstraction level, this is only the world-space 
     * bounds stored in @ref m_WorldBounds; subclasses may use this method to (re)compute additional bounds if necessary, or any data that 
     * depends on the bounds. Whenever bound-dependent data is requested through a public interface, @ref RecalculateBoundsIfNecessary should 
     * be called first to ensure bound correctness, which will in turn call this method if it turns out that they're outdated.
     * 
     * @see m_BoundsValid
     * @see RecalculateBoundsIfNecessary
     */
    virtual void CalcBounds() = 0;

    /// Returns the world-space axis-aligned bounds of this object.
    const CBoundingBoxAligned& GetWorldBounds()
    {
        RecalculateBoundsIfNecessary();
        return m_WorldBounds;
    }

    /**
     * Marks the bounds as invalid. This will trigger @ref RecalculateBoundsIfNecessary to recompute any bound-related data the next time
     * any bound-related data is requested through a public interface -- at least, if you've made sure to call it before returning the
     * stored data.
     */
    virtual void InvalidateBounds() { m_BoundsValid = false; }

    // Set the object renderdata and free previous renderdata, if any.
    void SetRenderData(CRenderData* renderdata)
    {
        delete m_RenderData;
        m_RenderData = renderdata;
    }

    /// Return object renderdata - can be null if renderer hasn't yet created the renderdata
    CRenderData* GetRenderData() { return m_RenderData; }

protected:
    /// Factored out so subclasses don't need to repeat this if they want to add additional getters for bounds-related methods
    /// (since they'll have to make sure to recalc the bounds if necessary before they return it).
    void RecalculateBoundsIfNecessary()
    {
        if (!m_BoundsValid) {
            CalcBounds();
            m_BoundsValid = true;
        }
    }

protected:
    /// World-space bounds of this object
    CBoundingBoxAligned m_WorldBounds;
    // local->world space transform
    CMatrix3D m_Transform;
    // world->local space transform
    CMatrix3D m_InvTransform;
    // object renderdata
    CRenderData* m_RenderData;

    /**
     * Remembers whether any bounds need to be recalculated. Subclasses that add any data that depends on the bounds should 
     * take care to consider the validity of the bounds and recalculate their data when necessary -- overriding @ref CalcBounds
     * to do so would be a good idea, since it's already set up to be called by @ref RecalculateBoundsIfNecessary whenever the
     * bounds are marked as invalid. The latter should then be called before returning any bounds or bounds-derived data through
     * a public interface (see the implementation of @ref GetWorldBounds for an example).
     * 
     * @see CalcBounds
     * @see InvalidateBounds
     * @see RecalculateBoundsIfNecessary
     */
    bool m_BoundsValid;
};

#endif