Hi Egon,

I read in this thread that additional color is multiplied with the existing color. That would explain why my black object seems to ignore the additional color. However, setting an additional color of BLACK on a colored object, does not result in a BLACK object. So it's not a simple multiplication.

Also, your documentation states the color is added:

public void setAdditionalColor(RGBColor col)
Sets the additional color for this object. This color will be added to the regular color of each vertex (given by ambient, diffuse and specular lighting).

So I'm a bit confused here: Now how does additionalColor work exactly?

Tnx

I'm using the latest I could find: 1.27

Almost there... only one tiny problem. I'm doing this in my onDrawFrame() method:

      fb.clear(back);
      world.renderScene(fb);
      world.draw(fb);

      fb.blit(fuelMeter,0,0,0,0,256,256,200,200,100,false);

      meterWorld.renderScene(fb);
      meterWorld.draw(fb);
      fb.display();
So first I draw my world containing the actual game objects, then I blit the static part of the fuel meter on top of it, and finally I draw the world containing nothing but my fuel indicator line on top of that. It all works great, except for 1 tiny detail:

The color of the polyline in the "meterWorld" is always white!? Even though it is defined as red:

fuelLine = new Polyline(new SimpleVector[] { new SimpleVector(-20,0,20), new SimpleVector(20,20,20) }, RGBColor.RED);
After some trail-and-error I found that removing the fb.blit() call fixes the issue, thus my Polyline is actually red then.

Why does this blit affect the color of the polyline? And how can I prevent that from happening?

Hi Egon,

Using reproject2D3DWS() does not seem to change a lot, my line is still just 3 or 4 pixels in the middle of the screen. Also, I've noticed that when I move the cam around, the reprojected lines move as well. Even though I am calling reproject2D3DWS() after every camera move. The idea is that the lines remain static on screen, like an overlay.

As the camera is passed as an argument into the reproject2D3DWS() method, I expected the method to come up with 3D coordinates that result in the exact same 2D coordinates, even when the cam is moved.

I'm still missing a vital piece. I think we need an example here to clarify things. I used your "hello world" app to demonstrate what I'm doing:

package com.example.line2don3d;

import java.lang.reflect.Field;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLDisplay;
import javax.microedition.khronos.opengles.GL10;

import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
import android.view.MotionEvent;

import com.threed.jpct.*;

public class HelloWorld extends Activity {

  public final static float PI = (float)Math.PI;
  public final static SimpleVector XAXIS = new SimpleVector(1,0,0);
  public final static SimpleVector YAXIS = new SimpleVector(0,1,0);
  public final static SimpleVector ZAXIS = new SimpleVector(0,0,1);
  public final static float DEGtoRAD = PI/180;

  // Used to handle pause and resume...
  private static HelloWorld master = null;

  private GLSurfaceView mGLView;
  private MyRenderer renderer = null;
  private FrameBuffer fb = null;
  private World meterWorld = null;
  private RGBColor back = new RGBColor(0,0,0);

  private float touchTurn = 0;
  private float touchTurnUp = 0;

  private float xpos = -1;
  private float ypos = -1;

  private Camera cam = null;
  private float camX = 100;
  private float camY = 0;

  private Polyline fuelLine = null;

  protected void onCreate(Bundle savedInstanceState) {

    Logger.log("onCreate");

    if (master != null) {
      copy(master);
    }

    super.onCreate(savedInstanceState);
    mGLView = new GLSurfaceView(getApplication());

    mGLView.setEGLConfigChooser(new GLSurfaceView.EGLConfigChooser() {
      public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display) {
        // Ensure that we get a 16bit framebuffer. Otherwise, we'll fall
        // back to Pixelflinger on some device (read: Samsung I7500)
        int[] attributes = new int[] { EGL10.EGL_DEPTH_SIZE, 16, EGL10.EGL_NONE };
        EGLConfig[] configs = new EGLConfig[1];
        int[] result = new int[1];
        egl.eglChooseConfig(display, attributes, configs, 1, result);
        return configs[0];
      }
    });

    renderer = new MyRenderer();
    mGLView.setRenderer(renderer);
    setContentView(mGLView);
  }

  @Override
  protected void onPause() {
    super.onPause();
    mGLView.onPause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    mGLView.onResume();
  }

  @Override
  protected void onStop() {
    super.onStop();
  }

  private void copy(Object src) {
    try {
      Logger.log("Copying data from master Activity!");
      Field[] fs = src.getClass().getDeclaredFields();
      for (Field f : fs) {
        f.setAccessible(true);
        f.set(this, f.get(src));
      }
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  public boolean onTouchEvent(MotionEvent me) {

    if (me.getAction() == MotionEvent.ACTION_DOWN) {
      xpos = me.getX();
      ypos = me.getY();
      return true;
    }

    if (me.getAction() == MotionEvent.ACTION_UP) {
      xpos = -1;
      ypos = -1;
      touchTurn = 0;
      touchTurnUp = 0;
      return true;
    }

    if (me.getAction() == MotionEvent.ACTION_MOVE) {
      float xd = me.getX() - xpos;
      float yd = me.getY() - ypos;

      xpos = me.getX();
      ypos = me.getY();

      touchTurn = xd / -100f;
      touchTurnUp = yd / -100f;
      return true;
    }

    try {
      Thread.sleep(15);
    } catch (Exception e) {
      // No need for this...
    }

    return super.onTouchEvent(me);
  }

  protected boolean isFullscreenOpaque() {
    return true;
  }

  class MyRenderer implements GLSurfaceView.Renderer {

    public MyRenderer() {
    }

    public void onSurfaceChanged(GL10 gl, int w, int h) {
      if (fb != null) {
        fb.dispose();
      }
      fb = new FrameBuffer(gl, w, h);

      if (master == null) {

        meterWorld = new World();
        meterWorld.setAmbientLight(100, 100, 100);

        Light sun = new Light(meterWorld);
        sun.setIntensity(255,255,255);
        sun.setPosition(new SimpleVector(100,0,0));

        cam = meterWorld.getCamera();
        cam.setPosition(camX,camY,0);
        cam.setOrientation(new SimpleVector(-1,0,0),ZAXIS);

        Object3D cube = Primitives.getCube(10);
        cube.setAdditionalColor(0xff,0xff,0);
        cube.setOrigin(SimpleVector.ORIGIN);
        cube.build();
        meterWorld.addObject(cube);

        fuelLine = new Polyline(new SimpleVector[] { new SimpleVector(-20,0,20), new SimpleVector(20,20,20) }, RGBColor.RED);
        fuelLine.setWidth(3);
        meterWorld.addPolyline(fuelLine);

        if (master == null) {
          Logger.log("Saving master Activity!");
          master = HelloWorld.this;
        }
      }
    }

    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    }

    private float fuel = 0;

    public void onDrawFrame(GL10 gl) {
      if (touchTurn != 0)
      {
        camY += touchTurn*10;
        cam.setPosition(camX,camY,0);
        cam.setOrientation(new SimpleVector(-1,0,0),ZAXIS);
        touchTurn = 0;
      }

      if (touchTurnUp != 0)
      {
        camX += touchTurnUp*10;
        cam.setPosition(camX,camY,0);
        cam.setOrientation(new SimpleVector(-1,0,0),ZAXIS);
        touchTurnUp = 0;
      }

      fuel += 0.01; // make the fuel line spin around and  around

      float angle = (-60+fuel*120)*DEGtoRAD;
      int x = 200;
      int y = 200;
      float r = 50;

      SimpleVector[] vectors = new SimpleVector[]
        {
          Interact2D.reproject2D3DWS(cam,fb,x,y),
          Interact2D.reproject2D3DWS(cam,fb,(int)(x+Math.sin(angle)*r+0.5),(int)(y-Math.cos(angle)*r+0.5))
        };
      fuelLine.update(vectors);

      fb.clear(back);
      meterWorld.renderScene(fb);
      meterWorld.draw(fb);
      fb.display();
    }
  }
}

What I'm getting with this, is a yellow cube on the origin, and inside the cube (so zoom in A LOT by sliding down) I find my little line that is spinning around. What I want is a spinning line around the actual sceen coordinate 200,200 with a radius of 50 pixels. What to do?

Yes, like a real fuel indicator you find in most cars. However, I do not want to draw this line in 3D space. It must somehow be possible to blit a line directly into jPCT's Framebuffer, so in real plain old 2D.

I've come up with the following:

Bitmap bmp = Bitmap.createBitmap(100,100,Bitmap.Config.RGB_565);
Canvas c = new Canvas(bmp);
Paint p = new Paint();
p.setColor(0xffffffff);

then in the onDrawFrame() method:

framebuffer.blit(fuelMeter,0,0,10,10,100,100,true); // blit the fuel meter without the line-indicator
// then make the line-indicator
bmp.eraseColor(0);
c.drawLine(10,10,90,90,p); // this is a static line, but of course the coordinates should move
Texture t = new Texture(bmp);
framebuffer.blit(t,0,0,10,10,100,100,true);

It works OK, except after a few seconds I get an Out of Memory error:

09-04 16:40:53.240: E/dalvikvm-heap(18607): Out of memory on a 65552-byte allocation.
09-04 16:40:53.240: I/dalvikvm(18607): "GLThread 6483" prio=5 tid=13 RUNNABLE
09-04 16:40:53.240: I/dalvikvm(18607):   | group="main" sCount=0 dsCount=0 obj=0x41244200 self=0x2170230
09-04 16:40:53.240: I/dalvikvm(18607):   | sysTid=18628 nice=0 sched=0/0 cgrp=default handle=34429144
09-04 16:40:53.240: I/dalvikvm(18607):   | schedstat=( 0 0 0 ) utm=874 stm=256 core=0
09-04 16:40:53.240: I/dalvikvm(18607):   at com.threed.jpct.GLRenderer.convertTexture(GLRenderer.java:~868)
09-04 16:40:53.240: I/dalvikvm(18607):   at com.threed.jpct.GLRenderer.blit(GLRenderer.java:1381)
09-04 16:40:53.240: I/dalvikvm(18607):   at com.threed.jpct.GLRenderer.blitTexture(GLRenderer.java:1747)

So probably instantiating a new Texture on every frame is not a good idea, but I see no possibility to re-use an existing Texture. Or maybe I'm using an incorrect approach alltogether.

Any help would be appreciated!

Hi Egon,

It's a good idea to come up with the needed angles right away from the calculations I'm doing anyway, still need to look at that. Meanwhile I took a look at the SimpleVector.getRotationMatrix() method you suggested... wondering what I could do with it, it turned out, that this was the solution for my question

I thought I'd post the solution here, just in case someone stumbles upon this page with a similar question.

Object3D[] group = something1;
SimpleVector original = something2;
SimpleVector destination = something3;

Matrix matrix = original.getRotationMatrix().invert();
matrix.matMul(destination.getRotationMatrix());

for (Object3D o: group)
{
  o.setRotationMatrix(matrix);
}
Tnx 4 your help!

Hi,

I have a group of Object3D's which I want to rotate "as a whole" into a different direction.

First, I'm giving all the objects the same rotation pivot point.
Then, I come up with a single SimpleVector which represents the current direction of the object group.
Then, after some calculations, I come up with a new SimpleVector, which indicates the desired new direction of my objects.

My question now is, how to use these 2 vectors to rotate my objects?

So let's say:

Object3D[] group = something1;
SimpleVector original = something2;
SimpleVector destination = something3;

for (Object3D o: group)
{
   // what to do with o?
}
Tnx!

I'm doing (almost) the same thing, but somehow rotateMesh() does not make the rotation permanent in my case.

I'm loading a 3DS model using Loader.load3DS(). Like bLAZY I also need to permanently rotate the object. My object consists of more than 1 object, so I'm wrapping them in a dummyObject first, which then is rotated:

Object3D[] puppetParts  = Loader.load3DS(stream,.1f);
Object3D puppet = Object3D.createDummyObj();
for (Object3D part: puppetParts)
  puppet.addChild(part);
puppet.rotateZ(-PI/2); // make puppet face positive X axis
puppet.rotateMesh(); // should make rotation permanent
puppet.clearRotation(); // but this rotates my puppet back!?
world.addObjects(puppetParts);
What am I doing wrong?

Thanks!