• Advertisement
Sign in to follow this  

A ring of vertices perpendicular to a given direction

This topic is 1658 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Good afternoon,
 
I'm currently developing a game for Android using OpenGL ES 2.0 where users fly through a tunnel, the goal being not to hit the walls.
 
The tunnel is randomly generated and it is composed of a series of interconnected rings. The rings are supposed to be perpendicular to the direction of the tunnel. See this screenshot when things go well:
 
 [spoiler]tunnelflyer.png[/spoiler]

Things still look good in this screenshot, but as the tunnel drifts away from the Z axis, the rings do not rotate with it correctly, causing this nice round tunnel to gradually flatten out then turn into an unmanageable mess of lines.
 
Currently, here's the code that I use to generate the rings: (Java)
// Constructor
public TunnelSection(GameManager myRenderer, TunnelSection previous) {
        
        sectionTransform = new float[16];
        
        float ring_radius =  RING_MIN_RADIUS + (float)(Math.random()) * (RING_MAX_RADIUS - RING_MIN_RADIUS);
        
        if (previous != null){
            mDirection = previous.mDirection;
            
            Quaternion randomRot = new Quaternion();
            randomRot.fromAngles(((float)Math.random()-0.5f)/5f, ((float)Math.random()-0.5f)/5f, ((float)Math.random()-0.5f)/5f);
            mDirection = mDirection.mult(randomRot);
            mDirection.normalizeLocal();
            
            Vector3f delta = mDirection.mult(Vector3f.UNIT_Z);
            
            mPosition = new float[]{previous.mPosition[0]+delta.x, previous.mPosition[0]+delta.y, previous.mPosition[2]+delta.z};
        }
        else {
            mDirection = Quaternion.DIRECTION_Z;
            mPosition = new float[]{0,0,0};
        }
        
        ringCoords = new float[(COORDS_PER_VERTEX) * RING_VERTICE_COUNT];
        
        Vector3f vertLocal = Vector3f.UNIT_X;
        
        for (int itr=0;itr<RING_VERTICE_COUNT;itr++){
            vertLocal.set(android.util.FloatMath.sin((float)Math.PI * 2f * ((float)itr/(float)RING_VERTICE_COUNT )) * ring_radius,
                          android.util.FloatMath.cos((float)Math.PI * 2f * ((float)itr/(float)RING_VERTICE_COUNT )) * ring_radius,
                          0f);
            
            vertLocal = mDirection.mult(vertLocal);
            
            ringCoords[itr*3]   = vertLocal.x;
            ringCoords[itr*3+1] = vertLocal.y;
            ringCoords[itr*3+2] = vertLocal.z;
        }
// Initialize the rest...
Why is it that the rings do not rotate like they should? It must be something very simple, but I can't find it... Edited by Werner291

Share this post


Link to post
Share on other sites
Advertisement
It looks like you have a typo in your first if statement where you're calculating mPosition. You're adding delta.x and delta.y to previous.mPosition[0] when you may want previous.mPosition[1] + delta.y.

Share this post


Link to post
Share on other sites

Aaargh... sleep.png typos... Always such errors when I'm doing maths... Why do other people always see such stuff so easily? Thanks.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement