T:/Eigene Dateien/Visual Studio 2008/Projects/VisLuFramework/src/TransferFunctionTexture.cpp

//Includes
#include "TransferFunctionTexture.h"
#include <algorithm>

#include "utility.h"
#include "Colours.h"

using namespace Colours;

//Static variables
GLuint TransferFunctionTexture::bottomWindowTransferFunctionTextureID = -1;
GLuint TransferFunctionTexture::renderWindowTransferFunctionTextureID = -1;

RGBA_Colour TransferFunctionTexture::transferFunctionTexture[transferFunctionTextureWidth];



void TransferFunctionTexture::initTransferFunctionTexture(int windowID, Window window)
{
        int initialWindow = glutGetWindow();
        glutSetWindow(windowID);

        GLuint* textureIDPointer = NULL;

        if(window == WINDOW_BOTTOM)
                textureIDPointer =  &bottomWindowTransferFunctionTextureID;
        if(window == WINDOW_RENDERING)
                textureIDPointer = &renderWindowTransferFunctionTextureID;


        if(textureIDPointer != NULL && windowID != GLuint(-1))
        {
                glGenTextures(1, textureIDPointer);

                get_errors();

                if(*textureIDPointer != GLuint(-1))
                {
                        get_errors();
                        glBindTexture(GL_TEXTURE_1D, *textureIDPointer);

                        glTexParameteri(GL_TEXTURE_1D,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_EDGE);
                        glTexParameteri(GL_TEXTURE_1D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
                        glTexParameteri(GL_TEXTURE_1D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

                        glTexImage1D(GL_TEXTURE_1D, 0, GL_RGBA, transferFunctionTextureWidth, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

                        get_errors();
                }
        }

        glutSetWindow(initialWindow);
}


void TransferFunctionTexture::refreshTransferTextureDataWithControlPoints()
{
        std::vector<TFControlPoint>::iterator currentLeft = TransferFunctionGUI::controlPoints.begin();
        std::vector<TFControlPoint>::iterator currentRight = (TransferFunctionGUI::controlPoints.begin() + 1);
        std::vector<TFControlPoint>::iterator controlPointsEnd = TransferFunctionGUI::controlPoints.end();

        //Run through x values and interpolate colours
        for(int x = 0; x < transferFunctionTextureWidth; ++x)
        {
                //Recalculate x to fit the dimensions of the transferFuncPicker which is where the controlpoints are located on
                float xRel = (x  / (float) transferFunctionTextureWidth);

                //Check if our position is between the same ControlPoints as before. If no - we need the following ones
                while(currentRight != controlPointsEnd && xRel > currentRight->m_pos.x)
                {
                        ++currentRight;
                        ++currentLeft;
                }

                //Exceeding last right point
                if(currentRight == controlPointsEnd && xRel > currentLeft->m_pos.x)
                {
                        float interPolBalance = (xRel - currentLeft->m_pos.x) / (float)(1.f - currentLeft->m_pos.x);
                        GLubyte leftAlpha = (GLubyte)(255 * currentLeft->m_pos.y);
                        GLubyte transparency = linearInterpolationAlpha
                                (interPolBalance,
                                leftAlpha,
                                (GLubyte)0
                                );
                        transferFunctionTexture[x] = RGBA_Colour(toRGB(currentLeft->getColourLab()), transparency);
                }
                //Being before first left point
                else if((currentLeft != controlPointsEnd) && xRel < currentLeft->m_pos.x)
                {
                        float interPolBalance = (currentLeft->m_pos.x - xRel) / currentLeft->m_pos.x;
                        GLubyte leftAlpha = (GLubyte)(255 * currentLeft->m_pos.y);
                        GLubyte transparency = linearInterpolationAlpha
                                (interPolBalance,
                                leftAlpha,
                                (GLubyte)0
                                );
                        transferFunctionTexture[x] = RGBA_Colour(toRGB(currentLeft->getColourLab()), transparency);
                }//Normal
                else
                {
                        float interPolBalance = TransferFunctionGUI::calcInterpolationValueBetweenControlPoints((int)(xRel * TransferFunctionGUI::g_iTransferFuncPickerWidth), currentLeft, currentRight);
                        GLubyte transparency = linearInterpolationAlpha
                                (interPolBalance,
                                (GLubyte)(255 * currentLeft->m_pos.y),
                                (GLubyte)(255 * currentRight->m_pos.y)
                                );
                        RGB_Colour& rgbResult = TransferFunctionGUI::interpolateControlPointColours(interPolBalance, currentLeft, currentRight);
                        transferFunctionTexture[x].setColour(rgbResult, transparency);
                }
        }
}



void TransferFunctionTexture::refreshTransferFunctionTextureData()
{
        //Special case: No points
        if(TransferFunctionGUI::controlPoints.size() == 0)
        {
                for(int x = 0; x < transferFunctionTextureWidth; ++x)
                        transferFunctionTexture[x] = RGBA_Colour((GLubyte)0, (GLubyte)0, (GLubyte)0, (GLubyte)0);
        }
        else
        {
                refreshTransferTextureDataWithControlPoints();
        }
}


void TransferFunctionTexture::copyDataToTransferFunctionTexture(int windowID, Window window)
{
        int initialWindow = glutGetWindow();
        glutSetWindow(windowID);

        GLuint* textureIDPointer = NULL;

        if(window == WINDOW_BOTTOM)
                textureIDPointer =  &bottomWindowTransferFunctionTextureID;
        if(window == WINDOW_RENDERING)
                textureIDPointer = &renderWindowTransferFunctionTextureID;

        if(textureIDPointer != NULL && windowID != GLuint(-1) && *textureIDPointer != GLuint(-1))
        {
                glBindTexture(GL_TEXTURE_1D, *textureIDPointer);
                glTexSubImage1D(GL_TEXTURE_1D, 0, 0, transferFunctionTextureWidth, GL_RGBA, GL_UNSIGNED_BYTE, transferFunctionTexture);
                get_errors();
        }

        glutSetWindow(initialWindow);
}