gls_triangle_storage.h

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/*! \file
 \brief  The disti::GlsTriangleStrip2D class.

 \par Copyright Information

 Copyright (c) 2017 by The DiSTI Corporation.<br>
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 Derivative Works based on this or other copyrighted DiSTI Software.

 NO WARRANTY. THE SOFTWARE IS PROVIDED "AS-IS," WITHOUT WARRANTY OF ANY KIND,
 AND ANY USE OF THIS SOFTWARE PRODUCT IS AT YOUR OWN RISK. TO THE MAXIMUM EXTENT
 PERMITTED BY APPLICABLE LAW, DISTI AND ITS SUPPLIERS DISCLAIM ALL WARRANTIES
 AND CONDITIONS, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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 LIMITATION OF LIABILITY. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW,
 IN NO EVENT SHALL DISTI OR ITS SUPPLIERS BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
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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;

class GlsTriangleStrip2D : public NonCopyable
{
public:
    /** Constant sizes of the primitive vertex attributes */
    static const GLuint VERT_SIZE = sizeof( V2f );
    static const GLuint TEX_SIZE  = sizeof( V2f );

    /** Constant offsets to the primitive vertex attributes. */
    static const GLuint VERT_OFFSET      = 0;
    static const GLuint TEX_COORD_OFFSET = VERT_SIZE;

    /** 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 );

    /** Returns 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