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[rwb1977]

So, here's a bizarre scenario that has been tying me up.

In this test case you will notice that as the camera moves from left to right, that the floor suddenly becomes transparent about 1/2 of the way on its path.  The expected behavior is that the two floor objects should always be transparent.

Furthermore, if you comment out the part in the test case that adds color values per vertex to the ceiling object, everything works as expected, all objects are transparent.

It's like the color array is messing with disabling the blend function.  The objects drawn *after* the object with the colors are being drawn opaque.  (I have sorting enabled).

Has anyone heard of color arrays conflicting with GL_BLEND?  The color values even have alpha values.

Code:

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package org.xith3d.test.render;

import org.jagatoo.input.InputSystem;
import org.jagatoo.input.devices.components.Key;
import org.jagatoo.input.events.KeyReleasedEvent;
import org.jagatoo.opengl.enums.DrawMode;
import org.jagatoo.opengl.enums.FaceCullMode;
import org.openmali.vecmath2.Colorf;
import org.openmali.vecmath2.Point3f;
import org.xith3d.base.Xith3DEnvironment;
import org.xith3d.loop.CanvasFPSListener;
import org.xith3d.loop.opscheduler.Animator;
import org.xith3d.loop.opscheduler.Interval;
import org.xith3d.render.Canvas3D;
import org.xith3d.render.Renderer;
import org.xith3d.resources.ResourceLocator;
import org.xith3d.scenegraph.BranchGroup;
import org.xith3d.scenegraph.Geometry;
import org.xith3d.scenegraph.PolygonAttributes;
import org.xith3d.scenegraph.TransparencyAttributes;
import org.xith3d.scenegraph.View;
import org.xith3d.scenegraph.primitives.Box;
import org.xith3d.scenegraph.primitives.SkySphere;
import org.xith3d.test.Xith3DTest;
import org.xith3d.test.util.TestUtils;
import org.xith3d.utility.commandline.BasicApplicationArguments;
import org.xith3d.utility.events.WindowClosingRenderLoopEnder;

@Xith3DTest.Description
(
    fulltext = {
                   "This test case demonstrates, how a semi-transparent",
                   "sphere can be rendered in Xith3D.."
               },
    authors = { "Marvin Froehlich (aka Qudus)" }
)
public class BlendingColorArrayTest extends Xith3DTest //InputAdapterRenderLoop
{
    private PolygonAttributes polyAttrs;
   
    @Override
    public void onKeyReleased( KeyReleasedEvent e, Key key )
    {
        switch ( key.getKeyID() )
        {
            case SPACE:
                polyAttrs.setFaceCullMode( FaceCullMode.values()[ (polyAttrs.getFaceCullMode().ordinal() + 1) % FaceCullMode.values().length ] );
                break;
           
            case ESCAPE:
                this.end();
                break;
        }
    }
   
    private BranchGroup createScene( Animator animator ) throws Exception
    {
        BranchGroup scene = new BranchGroup();
       
//        Cube background = new Cube( 10.0f, "stone.jpg" );
//        scene.addChild( background );
       
        float tval = 0.7f;
        TransparencyAttributes ta3 = new TransparencyAttributes( TransparencyAttributes.BLENDED, tval );
       
       
        Box b3 = new Box(new Point3f(395, 150f, -150), 800, 1f, 800, "jplogo.jpg");
        b3.getAppearance( true ).setTransparencyAttributes( ta3 );
        b3.getAppearance( true ).setPolygonAttributes( new PolygonAttributes( DrawMode.FILL, FaceCullMode.BACK ));
        scene.addChild( b3 );

        Box b4 = new Box(new Point3f(395, 140f, -150), 800, 1f, 800, "usa.jpg");
        b4.getAppearance( true ).setTransparencyAttributes( ta3 );
        b4.getAppearance( true ).setPolygonAttributes( new PolygonAttributes( DrawMode.FILL, FaceCullMode.BACK ));
       
        Box b2 = new Box(new Point3f(395, -4f, -150), 800, 1f, 800, "stone.jpg");
        b2.getAppearance( true ).setTransparencyAttributes( ta3 );
        b2.getAppearance( true ).setPolygonAttributes( new PolygonAttributes( DrawMode.FILL, FaceCullMode.BACK ));
        scene.addChild( b2 );
       
        Box b1 = new Box(new Point3f(395, -20f, -150), 800, 1f, 800, "wood.jpg");
        b1.getAppearance( true ).setTransparencyAttributes( ta3 );
        b1.getAppearance( true ).setPolygonAttributes( new PolygonAttributes( DrawMode.FILL, FaceCullMode.BACK ));
        scene.addChild( b1 );

        //* adding colors messes up blending.
        Geometry geom = b4.getGeometry();
        int numVerts = geom.getVertexCount();
        Colorf[]colors = new Colorf[numVerts];
        for (int i = 0; i < colors.length; i++)
        {
        colors[i] = new Colorf(.9f, 1, .9f, 1-tval);
        }
        geom.setColors(0, colors);
        //*/
       
        scene.addChild( b4 );
       
        getOperationScheduler().addInterval( new Interval( 100L )
        {
            @Override
            protected void onIntervalHit( long gameTime, long frameTime, TimingMode timingMode )
            {
            View view = env.getView();
            Point3f pos = view.getPosition();
            long curTime = System.nanoTime();
            float elapsedSecs = (curTime - startTime)*1e-9f;
            float period = 24;
            float percent = (float)(1-(.5f*Math.cos(Math.PI*2*(elapsedSecs % period)/period)+.5f));
            pos.setX( percent*(900) - 75);
            view.setPosition(pos);
           
            }
        } );
       
       
        return ( scene );
    }
   
    long startTime = System.nanoTime();
    Xith3DEnvironment env;
   
    public BlendingColorArrayTest( BasicApplicationArguments arguments ) throws Throwable
    {
        super( arguments.getMaxFPS() );
       
        env = new Xith3DEnvironment( this );
       
        ResourceLocator resLoc = TestUtils.createResourceLocator();
       
        env.getRenderer().setTransparentSortingPolicy(Renderer.TransparentSortingPolicy.SORT_BOUNDING_SPHERE_AND_EYE_RAY_INTERSECTION);
       
        resLoc.createAndAddTSL( "textures" );
       
        SkySphere skySphere = new SkySphere("reflectbg.jpg");
env.addRenderPass( skySphere );
       
        env.addPerspectiveBranch( createScene( this.getAnimator() ) );
       
        Canvas3D canvas = createCanvas( arguments.getCanvasConstructionInfo(), getClass().getSimpleName() );
       
        canvas.getRenderOptions().setLightingEnabled(false);
       
        env.addCanvas( canvas );
       
        canvas.addWindowClosingListener( new WindowClosingRenderLoopEnder( this ) );
        this.addFPSListener( new CanvasFPSListener( canvas ) );
       
        InputSystem.getInstance().registerNewKeyboardAndMouse( canvas.getPeer() );
    }
   
    public static void main( String[] args ) throws Throwable
    {
    BlendingColorArrayTest test = new BlendingColorArrayTest( parseCommandLine( args ) );
       
        test.begin();
    }
}

[Marvin Fröhlich]

I don't know that bug. An as I see, you've used the BleedingBlendingTest to create your test. The BBT demonstrates, that sorting works properly in Xith3D. So I would expect, it also works for your case. Looks like your suspicion is correct. Though this is pretty unexpectional.

Btw. you don't need your startTime and curTime. This is, what gameTime is for. Simply use the provided to convert the gameTime parameter to seconds. You possibly need to start the RenderLoop with mode NANOSECONDS. Anyway, let the engine do this work for you, if it can .

Marvin

[rwb1977]

I've scanned the xith engine, and can only find one place that blending is disabled, in the coloring/transparency state unit.  Therefore I do not think the xith engine is doing anything wrong.  The sorting algorithm puts the two ceiling objects first, and then the floor objects, and the ceiling object has a color array.  So it's as if when the "color array" state is disabled after drawing the ceiling object and prior to drawing the floor object, blending gets disabled--it's at this point blending needs to be reset, perhaps?

If the camera is moved to be closer to the ceiling than the floor, then the floor objects are sorted first, and then the ceiling, and everything is transparent.

[rwb1977]

I have a fix I'll commit soon.

[Agrv]

Rwb1977, what about the patch that you mentioned? Is is ready?