gls_triangle_storage.h

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/*! \file
 \brief  The disti::GlsTriangleStrip2D class.
 
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 */
 
#ifndef GLS_TRIANGLE_STORAGE_H
#define GLS_TRIANGLE_STORAGE_H
 
#include "dynamic_array.h"
#include "gls_gl.h"
#include "gls_include.h"
#include "gls_primitive_storage_types.h"
#include "gls_state_manager.h"
#include "non_copyable.h"
#include "vertex.h"
 
namespace disti
{
class Image;
 
/// \details The GlsTriangleStrip2D class. Wraps an OpenGL triangle strip drawable.
class GlsTriangleStrip2D : public NonCopyable
{
public:
    static const GLuint VERT_SIZE = sizeof( V2f ); ///< Size of a vertex in bytes.
    static const GLuint TEX_SIZE  = sizeof( V2f ); ///< Size of a texture coordinate in bytes.
 
    /// Constant offsets to the primitive vertex attribute.
    /// \note Theoretically should be GLuints, but OpenGL's functions to pass integer offsets as pointers.
    static const void* const VERT_OFFSET;
 
    /// Constant offsets to the primitive texture coordinate attribute.
    /// \note Theoretically should be GLuints, but OpenGL's functions to pass integer offsets as pointers.
    static const void* const TEX_COORD_OFFSET;
 
    /** Default constructor
     */
    GlsTriangleStrip2D();
 
    /** Destructor
     */
    virtual ~GlsTriangleStrip2D();
 
    /** Sets this object into strip building mode.  During strip building mode the user adds individual triangles to the strip
      * When strip building mode is finished, the object will create a triangle strip from the individual triangles
      * \pre none
      * \post _stripified == false
      */
    void StartBuildingStrip();
 
    /** Set the texture to be used for this triangle strip.  The triangle strip may only have one texture, so it is an error to call this
      * more than once after StartBuildingStrip() has been called.
      * \pre  _texture == NULL && _stripified == false
      * \post _texture == img
      * \param image The texture to assign, or NULL if no texture
      */
    void SetTexture( Image* image );
 
    /** Set the texture coordinates to be used for the next triangle that is added (or subsequent triangles if this is not called again
      * \param x1 X coord of vertex 1
        * \param y1 Y coord of vertex 1
      * \param x2 X coord of vertex 2
      * \param y2 Y coord of vertex 2
      * \param x3 X coord of vertex 3
      * \param y3 Y coord of vertex 3
      * \pre  _texture != NULL && _stripified == false
      * \post _currentTex contains input values
      */
    void SetTexCoords( const float x1, const float y1, const float x2, const float y2, const float x3, const float y3 );
 
    /** Add the next triangle to the strip.  Must be connected using previous two vertices of strip or be degenerate
     * \param x1 X coord of vertex 1
     * \param y1 Y coord of vertex 1
     * \param x2 X coord of vertex 2
     * \param y2 Y coord of vertex 2
     * \param x3 X coord of vertex 3
     * \param y3 Y coord of vertex 3
     * \pre _stripified == false
     * \post _numTriangles++, triangle is added to strip
     */
    void AddTriangle2D( const float x1, const float y1, const float x2, const float y2, const float x3, const float y3 );
 
    /** Finish building strip and bake it to a VBO
      * \param stateManager  StateManager object to issue GL commands to
      * \pre  _stripified == false
      * \pre  _stripified == true
      */
    void Bake( IGlsStateManager* stateManager );
 
    /** Draw the triangle strip
        * \param stateManager  StateManager object to issue GL commands to
      * \param enableTexture  True if strip will be drawn textured
      * \pre _stripified == true
      * \post  The strip is drawn
      */
    void Draw( IGlsStateManager* stateManager, const bool enableTexture );
 
    /// \return The number of triangles in this strip.
    unsigned int GetNumTriangles()
    {
        return _numTriangles;
    }
 
protected:
    unsigned int _numTriangles; /**< The number of triangles in the strip */
    unsigned int _stripSize;    /**< The number of vertices in the strip */
 
    DynamicArray<V2f_T2f, true> _vertData;        /**< DynamicArray to store vertex and texture coordinates */
    V2f                         _currentTex[ 3 ]; /**< Current texture coordinates supplied for current triangle
                                                 (Texture coordinates are not required to change per triangle)
                                                   Used only while building list.
                                            */
 
    Image* _texture; /**< Texture to use when drawing strip.  NULL if untextured */
 
    unsigned int _vboHandle;     /**< VBO Handle for this triangle strip */
    unsigned int _vboBufferSize; /**< Size of the VBO buffer.  Cached to so that when a strip is cleared and reset
                                                 we will only reallocate the VBO when its size changes. */
    bool         _stripified;    /**< True if triangles have been created into a strip */
 
    /** Allocate the next triangle in the set of ordered, connected triangles */
    void AllocateNextTriangle();
 
    /** Convert the set of ordered, connected triangles in this object into tristrip
      * \pre _stripified == false
      * \pre _stripified == true
       */
    void Stripify();
};
 
} // namespace disti
 
#endif