tfglwidget.cpp

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#include "VolumeBuffer.h"
#include <QtGui>
#include <QtOpenGL>

#include <math.h>

#include "tfglwidget.h"
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

tfGLWidget::tfGLWidget(QWidget *parent)
    : QGLWidget(parent)
{
        setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        m_tf_texture = new unsigned char [256*64*4];
}

tfGLWidget::~tfGLWidget()
{
    makeCurrent();
        delete [] m_tf_texture;
}

QSize tfGLWidget::minimumSizeHint() const
{
    return QSize(50, 50);
}

QSize tfGLWidget::sizeHint() const
{
    return QSize(256, 64);
}

void tfGLWidget::setTFID(GLuint tfid)
{
        //deleteTexture(m_tfid);
        m_tfid = tfid;
}

void tfGLWidget::setTFImage(QImage &tfimg)
{
        m_tfimg = tfimg;
        updateGL();
}

void tfGLWidget::initializeGL()
{
        //glutInitDisplayMode (GLUT_RGBA | GLUT_DOUBLE);
        glewInit();
    qglClearColor(trolltechPurple.dark());
        glShadeModel (GL_FLAT);
        glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
        glEnable(GL_TEXTURE_2D);
}

void tfGLWidget::paintGL()
{
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glLoadIdentity();
    glTranslated(0.0, 0.0, 0.0);

        glEnable(GL_TEXTURE_2D);
        glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

        //GLuint tf_texture_id;
        //send texture to GPU
        deleteTexture(m_tfid);
        //m_tfid = bindTexture(m_tfimg, GL_TEXTURE_2D, GL_RGBA);

        glGenTextures(1, &m_tfid);

        int iy = 0;
        int ix;
        //reset transfer function values to zeros
        memset(m_tf_texture,0,256*64*4*sizeof(unsigned char));
                
        //fill values from image
        for (iy = 0; iy < 64; iy++)
        {
                for (ix = 0; ix < 256; ix++)
                {
                        QRgb tfc = m_tfimg.pixel(ix,0);

                        m_tf_texture[((256)*iy + ix)*4 + 0] = (GLubyte) qRed(tfc);
                        m_tf_texture[((256)*iy + ix)*4 + 1] = (GLubyte) qGreen(tfc);
                        m_tf_texture[((256)*iy + ix)*4 + 2] = (GLubyte) qBlue(tfc);
                        m_tf_texture[((256)*iy + ix)*4 + 3] = (GLubyte) qAlpha(tfc);
                }
        }

        //bind texture with texture name
        glBindTexture(GL_TEXTURE_2D,m_tfid);
        
        //texture setup
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        
        GLint mode = GL_CLAMP;
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, mode);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, mode);

        //bind slice data
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 64, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_tf_texture);

        glBegin(GL_QUADS);
        
        glTexCoord3f(0.0f, 0.0f, 0.0f); glVertex3f (-1.0f, -1.0f, 0.0f);
        glTexCoord3f(1.0f, 0.0f, 0.0f); glVertex3f (1.0f, -1.0f, 0.0f);
        glTexCoord3f(1.0f, 1.0f, 0.0f); glVertex3f (1.0f, 1.0f, 0.0f);
        glTexCoord3f(0.0f, 1.0f, 0.0f); glVertex3f (-1.0f, 1.0f, 0.0f);
        
        glEnd();

        glFlush();
        glDisable(GL_TEXTURE_2D);

}

void tfGLWidget::resizeGL(int width, int height)
{
    int side = qMin(width, height);
    //glViewport((width - side) / 2, (height - side) / 2, side, side);

   glViewport (0, 0, (GLsizei) width, (GLsizei) height); 
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity ();
   glFrustum (-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
   glMatrixMode (GL_MODELVIEW);
}

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