Volume Rendering : can not mix shader based volume with legacy opengl polygons

[jzy3d]

One can't mix colored polygons with volume properly

• Polygon render black
• Polygon are not visible behind the translucent parts of the volume

macOS 10.12

Ubuntu 20.04 and macOS 11.4 on Silicon

Whereas the polygon have the following colors

Can be reproduced with 2.0.1-SNAPSHOT and the following program

import java.nio.ByteBuffer;
import org.jzy3d.analysis.AWTAbstractAnalysis;
import org.jzy3d.analysis.AnalysisLauncher;
import org.jzy3d.chart.factories.AWTChartFactory;
import org.jzy3d.chart.factories.AWTPainterFactory;
import org.jzy3d.chart.factories.ChartFactory;
import org.jzy3d.chart.factories.IPainterFactory;
import org.jzy3d.colors.Color;
import org.jzy3d.colors.ColorMapper;
import org.jzy3d.colors.colormaps.ColorMapRainbow;
import org.jzy3d.maths.BoundingBox3d;
import org.jzy3d.plot3d.primitives.Polygon;
import org.jzy3d.plot3d.primitives.RandomGeom;
import org.jzy3d.plot3d.primitives.volume.Texture3D;
import org.jzy3d.plot3d.rendering.canvas.Quality;
import com.jogamp.opengl.util.GLBuffers;

public class VolumeDemo_Shaders extends AWTAbstractAnalysis {
  public static void main(String[] args) throws Exception {
    AnalysisLauncher.open(new VolumeDemo_Shaders());
  }

  @Override
  public void init() {

    ColorMapper colorMapper = new ColorMapper(new ColorMapRainbow(), 0, 1, new Color(1, 1, 1, 1.5f));

    ByteBuffer buffer = GLBuffers.newDirectByteBuffer(10 * 10 * 10 * 4);
    // make some kind of volume
    for (float x = 0; x < 2; x += 0.2) {
      for (float y = 0; y < 2; y += 0.2) {
        for (float z = 0; z < 2; z += 0.2) {
          buffer.putFloat((float) Math.sin(x * y * z));
        }
      }
    }

    Texture3D volume = new Texture3D(buffer, new int[] {10, 10, 10}, (float) 0, (float) 1,
        colorMapper, new BoundingBox3d(1, 10, 1, 10, 1, 10));
    
    RandomGeom rg= new RandomGeom();
    Polygon p1 = rg.poly(0, 0, 2, 10, 10, true, Color.RED);
    Polygon p2 = rg.poly(0, 0, 4, 10, 10, true, Color.GREEN);
    Polygon p3 = rg.poly(0, 0, 6, 10, 10, true, Color.BLUE);

    // Create a chart
    IPainterFactory p = new AWTPainterFactory();
    //p.setDebugGL(true);
    ChartFactory f = new AWTChartFactory(p);
    chart = f.newChart(Quality.Intermediate());
    chart.add(volume);
    chart.add(p1);
    chart.add(p2);
    chart.add(p3);
  }
}

[jzy3d]

"Polygon are not visible behind the translucent parts of the volume" : this can be fixed by rendering the polygon first AND then the volume, which can be done by adding the volume last in the scene graph :

chart.add(p1);
chart.add(p2);
chart.add(p3);
chart.add(volume);

This raises the need for an order independent transparency renderer. This is currently in progress (in module jzy3d-depthpeeling, on this branch). Trying to apply it to this scene involving Texture3D

DepthPeelingPainterFactory p = new DepthPeelingPainterFactory();
p.setPeelingMethod(PeelingMethod.WEIGHTED_AVERAGE_MODE);
ChartFactory f = new AWTChartFactory(p);

lead to better rendering of the R,G,B planes but a volume coloring mess

Which renders quite the same when planes are removed

The depth peeling implementation used in this example is here :

• Main program handling shaders
• Vertex shader 1
• Vertex shader 2
• Fragment shader 1
• Fragment shader 2

@jacobfilik

[jzy3d]

See here an example of mixing volume and legacy polygons

https://forum.jogamp.org/TextRender-only-work-after-reshape-with-GL-TEXTURE2-binding-td4041609.html#a4041621