Contour Plot from Matrix

Version Info

Minimum Origin Version Required: Origin 7.5

Example

This example to show how to add contour plotting and then use the following two functions to custom Z levels and fill colors. Please refer to DataPlot::SetColormap for more information.

void plot_contour()
{
        MatrixPage mp;
        mp.Create("origin");
        MatrixLayer ml = mp.Layers(0);
        Matrix mat(ml);
        mat.SetSize(10, 10);
        for(int ii=0; ii<mat.GetNumRows();ii++)
                for(int jj=0; jj<mat.GetNumCols();jj++)
                        mat[ii][jj] = sin(ii+jj);
                
        MatrixObject mobj = ml.MatrixObjects();
        
        GraphPage gp;
        gp.Create("contour", CREATE_HIDDEN); // use template, create as hidden to avoid unneeded drawing    
        GraphLayer glay = gp.Layers();      
        int nPlot = glay.AddPlot(mobj, IDM_PLOT_CONTOUR);      
        glay.Rescale();
        
        DataPlot dp = glay.DataPlots(nPlot);
        if(dp)
        {
                set_contour_colormap(dp);
        }
        gp.SetShow();
}

void set_contour_colormap(DataPlot& dp)
{     
        vector vLevels;
        BOOL bLogScale;
        if( !dp.GetColormap(vLevels, bLogScale) )
                return;
        
        // shrink or extend z levels 
        int nLevels = vLevels.GetSize();
        if( nLevels >= 5)
                nLevels -= 2;
        else
                nLevels += 2;
        
        double min = vLevels[0], max = vLevels[nLevels-1];    
        double step = (max - min)/(nLevels-1);
        vLevels.Data(min, max, step);
        
        // set z levels
        if( !dp.SetColormap(vLevels) )
                return;    
        
        vector<uint> vColors(nLevels-1); // the size  of vColors must be nLevels-1
        for(int ii = 0; ii < vColors.GetSize(); ii++)
        {
                int gg = 255* ii / (nLevels-1);
                int bb = 255 * (nLevels-ii-1)/(nLevels-1);
                int nRGB = RGB(0, gg, bb);
                vColors[ii] = RGB2OCOLOR(nRGB);
        }
        
        // call DataPlot::SetColormap(const vector<double>& vz, BOOL bLogScale=FALSE) to set z levels
        if( !dp.SetColormap(vLevels) )
        {
                printf("Fail to set z levels\n");
                return;
        }
        
        // call DataPlot::SetColormap(TreeNode& trColormap) to set colormap
        Tree tr; 
        tr.ColorMap.Details.Colors.nVals = vColors;
        if(!dp.SetColormap(tr))
        {
                printf("Fail to set colormap\n");
                return;    
        }
        
}