volumerenderer_private.h

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#ifndef VOLUMERENDERER_PRIVATE_H
#define VOLUMERENDERER_PRIVATE_H

#include "volumerenderer.h"
#include "volumeloader.h"
#include "geometry.h"

//these are the only functions that we use that are not in GL 3.3
//instead of using the whole 4.2 context, we just import this one function manually
extern PFNGLBINDIMAGETEXTUREPROC __glBindImageTexture;
extern PFNGLDISPATCHCOMPUTEPROC __glDispatchCompute;

#define glBindImageTexture __glBindImageTexture 
#define glDispatchCompute __glDispatchCompute

//vertex attribute positions
#define ATTRPOS_VERTEX 0
#define ATTRPOS_COLOR 1

//tex unit positions
#define TEXUNIT_VOLUME 0
#define TEXUNIT_TRANSFUNC 1
//these are only temporarily used while loading the volume
#define TEXUNIT_INTENSITY 2
#define TEXUNIT_SMOOTH 3

//current slice texture
#define TEXUNIT_SLICE 4
//previous eye/intermediate buffer
#define TEXUNIT_PREVIOUS 5
//final intermediate buffer (for merging)
#define TEXUNIT_INTERMEDIATE 6

//image units (for shader-writable textures)
#define IMGUNIT_VOLUME 0
#define IMGUNIT_SMOOTH 1

//the maximal number of intersection points of a plane with a cube is 6, + 1 centroid vertex, +1 repeated vertex
#define SLICEBUFFER_STRIDE 8
//the buffer has storage for this amount of slices (i.e. is of size SLICEBUFFER_STRIDE * 3(xyz) * 4(float) * SLICEBUFFER_SLICECOUNT bytes in total)
#define SLICEBUFFER_SLICECOUNT 2048

//1s sync timeout
#define SYNC_TIMEOUT 1000000

struct VolumeRendererPrivate
{
    VolumeLoader* volLoader;
    QOpenGLDebugLogger* glLogger;

    Cube bBox;
    bool volumeLoaded,fixSlicingMatrix,renderBB,smoothVolume,showLightDir;
    VolumeMetaData currentVolume;
    QByteArray currentVolumeData; //this is only filled after loadVolume and before update() has finished

    QVector2D window;
    //light dir vector, and halfway vector
    QVector3D lightVec,halfVec;

    VolumeRenderer::ProjectionType projType;
    QMatrix4x4 mProj, view, mvp, mSlicing;

    int sliceCount,renderedSlices;

    bool doDOF;
    float focalPlaneDist,blurAmount;
    
    int winWidth,winHeight;

    /*
    This is the offset in the SLICE BUFFER, not the Z offset of the current slice!
    The value lies in [0, SLICEBUFFER_SLICECOUNT)
    */
    int currentSliceOffset;
    GLsync sliceSync[SLICEBUFFER_SLICECOUNT];

    QList<QString> glExtensions;
    
    
    float rotX,rotY,distance,sliceDelta;
    float lightAz,lightAngle;
    float gaussSigma;

    QElapsedTimer timer;
    qint64 frametime;
    struct
    {
        QOpenGLShaderProgram* blur;
        QOpenGLShaderProgram* merge;
        QOpenGLShaderProgram* transform;
        QOpenGLShaderProgram* color;
        QOpenGLShaderProgram* bBox;
        QOpenGLShaderProgram* slice;
        QOpenGLShaderProgram* gaussian;
        QOpenGLShaderProgram* gradient;
    } shaders;
    struct
    {
        //QOpenGLBuffer* uniformBuffer;
        QOpenGLBuffer* vBuffer;
        QOpenGLBuffer* lineBuffer;
        QOpenGLBuffer* sliceVBuffer;
        QOpenGLBuffer* iBuffer;
        size_t triangleIndexOffset, lineIndexOffset, sliceIndexOffset;
    } buffers;
    struct
    {
        QOpenGLVertexArrayObject* box;
        QOpenGLVertexArrayObject* line;
        QOpenGLVertexArrayObject* slice;
    } vaos;

    struct
    {
        QOpenGLFramebufferObject* slice;
        QOpenGLFramebufferObject* eye[2];
        QOpenGLFramebufferObject* intermediate[2];
        uint eDraw,eRead;
        uint iDraw,iRead;
    } fbos;

    struct
    {
        QOpenGLTexture* volume;
    } textures;

    VolumeRendererPrivate()
        : distance(2.0f),rotX(0),rotY(0),projType(VolumeRenderer::ProjectionType::Perspective),
        renderBB(true),sliceDelta(0.01f),window(0.0f,1.0f),frametime(0),volumeLoaded(false),fixSlicingMatrix(false),showLightDir(false),smoothVolume(true),lightAz(180.0f),lightAngle(15.0f),gaussSigma(0.6f),
        currentSliceOffset(0), focalPlaneDist(0.5f), blurAmount(0.5f), doDOF(true), sliceCount(0), renderedSlices(0)
    {
        fbos.slice = nullptr;
        fbos.eye[0] = fbos.eye[1] = nullptr;
        fbos.intermediate[0] = fbos.intermediate[1] = nullptr;
        fbos.eDraw = fbos.iDraw = 0;
        fbos.eRead = fbos.iRead = 1;

        for(int i =0;i<SLICEBUFFER_SLICECOUNT;++i)
        {
            sliceSync[i] = nullptr;
        }
    }
};

#endif