cockpit camera in flight simulator

[davbwild]

Hi ,
could someone please give some step-by-step details to handle a cockpit camera in a flight simulator ??
I can't manage to get the right moves along yaw,roll,pitch
My parameter target in gluLookat function is wrong ...
Thank you very much for you help

[BionicBytes]

Some one else is going to ask..so it may as well be me.
What is wrong with your code..can you describe the problem.
Post some code which handles the camera - use the [code ] [/code ] tags to make the code readable (don't include the extra space in the brackets though).

[RefleX]

Post some code and brush up on your matrix maths while you wait for a reply.

Rotation in a flight game works different since you want the relative rotation from your current rotation.
NewRotationMat = CurrentRotationMat*RelativeRotationMat;
Hope that helps somewhat.

[davbwild]

Ok thank you for your answer. I realized after posting that without code (I didn't mention that I work in Java (JOGL), it wouldn't mean a lot to the most helpful viewer
So here we are :
the main algorithm is quite basic :
GL_Renderer calls an Object Scene which draws the elements (the terrain and the plane)
here is the code of the call-back display() of GlRenderer:

 public void display(GLAutoDrawable drawable) {
        GL2 gl = drawable.getGL().getGL2();
        GLU glu = GLU.createGLU(gl);
 
        // Clear the drawing area
        gl.glClear(GL2.GL_COLOR_BUFFER_BIT | GL2.GL_DEPTH_BUFFER_BIT);
        // Reset the current matrix to the "identity"
        gl.glLoadIdentity();
 
        // on dessine la scene
        myScene.draw(gl, glu);

Then the scene draw method sets the cockpit camera with the right eye and right target (depending on the plane position and attitude)

public void draw(GL2 gl, GLU glu) {
 
        // TEST CAMERA TOUR
               // test avion
        myObj.setPosAtt(myMNT, myMNT.get_longUL()+myMNT.get_cellsize()*(1.1+step), myMNT.get_latUL()+myMNT.get_cellsize()*(1.+step), 820.f, 30.f, 0.f, 0.f);
 
 
            currentCamera.look(glu, gl, this.getAvion());

Then I draw the terrain (an height grid starting from (0,0,0) in the MODEL frame)
Then I draw the plane applying the moves according to:

public void display(GL2 gl, GLU glu) {
 
        myVBO.bind(gl);
 
        myIdx.bind(gl);
 
        myTexture.bind(gl);
 
      // gl.glLoadIdentity();
 
        gl.glTranslated(posAvion.x, posAvion.y, posAvion.z );
 
 
        gl.glRotated(getRoll(), 0.0, 0.0, 1.0);
 
        gl.glRotated(getPitch(), 1.0, 0.0, 0.0);
 
 
        gl.glRotated(getYaw(), 0.0, 1.0, 0.0);
 
        avion.draw(gl);
 
        // gl.glDrawElements(GL2.GL_TRIANGLES, myIdx.getCount(), GL2.GL_UNSIGNED_INT, 0);
    }

Then I define how to set camera eye and target by :
eye= plane position
up is y axis with the roll applied
target direction is plane position vector plus the direction of yaw and pitch rotations applied the Z axis (my plane is along Z axis)

  public void searchTarget(Obj plane, GL2 gl) {
        gl.glPushMatrix();
 
        gl.glRotated(plane.getRoll(), 0.0, 0.0, 1.0);
        System.out.println("ok");
        m1 = new float[16];
        gl.glGetFloatv(gl.GL_MODELVIEW_MATRIX, m1, 0);
 
        //vecteur Up
        vert = Vec4.multMatVec(m1, new Vec4(0.f, 1.f, 0.f, 1.f));
        super.setUp(new Vec3(vert.x, vert.y, vert.z));
 
 
 
 
        gl.glRotated(plane.getPitch(), 1.0, 0.0, 0.0);
 
 
        gl.glRotated(plane.getYaw(), 0.0, 1.0, 0.0);
        m2 = new float[16];
        gl.glGetFloatv(gl.GL_MODELVIEW_MATRIX, m2, 0);
        // vecteur direction regard
        dirEye = Vec4.multMatVec(m2, new Vec4(0.f, 0.f, 1.f, 1.f));
        sum=Vec3.vec1Plusvec2(plane.getPosAvion(), new Vec3(dirEye.x, dirEye.y, dirEye.z));
        // super.setTarget(Vec3.vec1Plusvec2(plane.getPosAvion(), new Vec3(dirEye.x,dirEye.y,dirEye.z)));
        super.setEye(new Vec3(radius*sum.x,radius*sum.y,radius*sum.z-6));
 
        gl.glPopMatrix();
 
    }

I hope it is clear enough
Thanks

[RefleX]

Deprecated OpenGL

The language is not such a problem you just need to do the translation.

public void display(GL2 gl, GLU glu)
{
        myVBO.bind(gl);
        myIdx.bind(gl);
        myTexture.bind(gl);
 
      // gl.glLoadIdentity();
 
        gl.glTranslated(posAvion.x, posAvion.y, posAvion.z );
 
     // Here is the piece you need to change
        gl.glPushMatrix();
 
        // get(Roll/Pitch/Yaw)() should reflect how much you want to rotate the ship in a single frame not it's actual rotation (think of it as velocity/torque)
        gl.glLoadMatrixf(avion.rotMat); // rotMat should be initialized as an identity matrix and is of type float[16]
        gl.glRotated(getRoll(), 0.0, 0.0, 1.0);
        gl.glRotated(getPitch(), 1.0, 0.0, 0.0);
        gl.glRotated(getYaw(), 0.0, 1.0, 0.0);
        gl.glGetFloatv(gl.GL_MODELVIEW_MATRIX, avion.rotMat, 0);
 
        gl.glPopMatrix();
 
        gl.glMultMatrixf(avion.rotMat);
     //
 
        avion.draw(gl);
 
        // gl.glDrawElements(GL2.GL_TRIANGLES, myIdx.getCount(), GL2.GL_UNSIGNED_INT, 0);
}

The code I replaced should work, you also need to change the following code...

  public void searchTarget(Obj plane, GL2 gl) {
        gl.glPushMatrix();
 
        gl.glRotated(plane.getRoll(), 0.0, 0.0, 1.0);
        System.out.println("ok");
        m1 = new float[16];
        gl.glGetFloatv(gl.GL_MODELVIEW_MATRIX, m1, 0);
 
        //vecteur Up
        vert = Vec4.multMatVec(m1, new Vec4(0.f, 1.f, 0.f, 1.f));
        super.setUp(new Vec3(vert.x, vert.y, vert.z));
 
 
 
 
        gl.glRotated(plane.getPitch(), 1.0, 0.0, 0.0);
 
 
        gl.glRotated(plane.getYaw(), 0.0, 1.0, 0.0);
        m2 = new float[16];
        gl.glGetFloatv(gl.GL_MODELVIEW_MATRIX, m2, 0);
        // vecteur direction regard
        dirEye = Vec4.multMatVec(m2, new Vec4(0.f, 0.f, 1.f, 1.f));
        sum=Vec3.vec1Plusvec2(plane.getPosAvion(), new Vec3(dirEye.x, dirEye.y, dirEye.z));
        // super.setTarget(Vec3.vec1Plusvec2(plane.getPosAvion(), new Vec3(dirEye.x,dirEye.y,dirEye.z)));
        super.setEye(new Vec3(radius*sum.x,radius*sum.y,radius*sum.z-6));
 
        gl.glPopMatrix();
 
    }

This piece of code is troublesome and I can only help you out with the code I use in C++, it will be up to you to convert it to Java.

// mat.rot() - extract the rotation part of the matrix, returns a matrix
cVec3 eye = ship->mat*cVec3(0, -ship->model->mesh->radius*3.0f, ship->model->mesh->radius*1.0f);
cVec3 centre = ship->mat*cVec3(0, 1000000.0f, 0);
cVec3 up = ship->mat.rot()*cVec3(0, 1, 0);
 
cMat4 view = cMat4::LookAt(eye, centre, up);

As I said, up to you to translate.

[davbwild]

Thank you very much for your help
I will try to change my code and let you know