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Renderer.h

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/*
    File:           Renderer.h

    Function:       Contains the definition for the renderer class. A 
                    particular graphics system must implement objects of this
                    type.

                    example use: 
                        r.Clear().Start(renPoly)
                            .Colour(cRed).Vertex(a).Vertex(b).Vertex(c)
                            .End().Show();
    
    Author(s):      Andrew Willmott

    Copyright:      (c) 1995-2000, Andrew Willmott
 */

#ifndef __Renderer__
#define __Renderer__

#include "gcl/Geometry.h"
#include "gcl/Colour.h"
#include "gcl/Image.h"
#include "gcl/Camera.h"
#include "cl/Action.h"


// --- The Renderer class -----------------------------------------------------


class Renderer;

typedef Action<Renderer>    RenderAction;
typedef Renderer            *RendererPtr;

enum RenderStyle            // Commands for point-series drawing
{
    renNone, 
    renPoints,
    renLines,
    renLineStrip,
    renLineLoop,
    renPoly,
    renTriangles,
    renTriStrip,
    renMaxStyles
};

class Renderable
{
public:
    virtual Void        Draw(Renderer &r) = 0;
};

class Renderer              // Abstract class for something you can render into
{
public:
    Renderer();
    
    virtual Void        Show() = 0;
    virtual Void        MakeCurrent() = 0;
    virtual Void        Print(ostream &s) = 0;
    
    Renderer            &Draw(Renderable &thing);
    Renderer            &Draw(Renderable *thing);
    virtual Renderer    &Begin(RenderStyle style) = 0;
    virtual Renderer    &End() = 0;

    virtual Renderer    &SetPoint(const Point &p) = 0;
    virtual Renderer    &SetNormal(const Point &p) = 0;
    virtual Renderer    &SetCoord(const Coord &c) = 0;
    virtual Renderer    &SetTexCoord(const Coord &c);
    virtual Renderer    &SetColour(const Colour &c) = 0;
    virtual Renderer    &SetColour(const Colour4 &c);

    virtual Renderer    &SetTransform(const Transform &t) = 0;
    virtual Renderer    &SetCamera(const Camera &c) = 0;
    virtual Renderer    &SetTexture(const Image *image);

    Void                SetBgColour(const Colour &c) { bgColour = c; };
    Colour              GetBgColour() { return(bgColour); };

    virtual Renderer    &Clear() = 0;
    virtual Renderer    &Pop() = 0;
    virtual Renderer    &Push() = 0;

    virtual Renderer    &GetImage(Image &image) = 0;
    virtual Renderer    &PutImage(const Image &image, Int x = 0, Int y = 0) = 0;

    // short-cuts

    Renderer            &P(const Point &p) {return(SetPoint(p));};
    Renderer            &P(const Coord &c) {return(SetCoord(c));};
    Renderer            &N(const Vector &p) {return(SetNormal(p));};
    Renderer            &C(const Colour &c) {return(SetColour(c));};
    Renderer            &C(const Colour4 &c) {return(SetColour(c));};
    Renderer            &T(const Coord &c) {return(SetTexCoord(c));};
    Renderer            &Xform(const Transform &t) {return(SetTransform(t));};
    Renderer            &Cam(const Camera &c) {return(SetCamera(c));};

                
protected:
    inline Void         SetWindow();

    Colour              bgColour;
    static Renderer     *sCurrentRenderer;
};

ostream &operator << (ostream &s, Renderer &gsr);

// --- Inlines ----------------------------------------------------------------


inline Void Renderer::SetWindow()
//  swap drawing contexts if necessary...
{
    if (this != sCurrentRenderer)
    {
        sCurrentRenderer = this;
        MakeCurrent();
    }
}

#endif

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