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Member Since 25 Jun 2012
Offline Last Active May 30 2014 10:50 AM

Topics I've Started

Managing shaders/materials

26 December 2013 - 06:19 AM

Hello, I'm trying to write a 3D engine, but I'm having some problems with the management of my shaders and materials.


Mostly, the problem is keeping the two seperate. Some things in my engine require texture splatting, others need to be reflective, others need to glow, yet others should look liquid, and then some more...


I was quite impressed by Ogre3D's material scripts, but I can't make heads or tails out of the enormous amount of source code.


My current approach is to try to automatically generate a shader program for every material, but this seems kinda wasteful. I might for example have two things in the game world that look exactly identical except for a different color.


Also, since the program generation is now locked away in the material, how to I implement things like tesselation and vertex manipulation?


This has been causing me headaches over the past couple days up to the point where I felt like just abandoning, but I'd at least like to understand this before I do.

A ring of vertices perpendicular to a given direction

07 July 2013 - 06:51 AM

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:

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);
            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,
            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...

Does the projection of a point onto a plane belong to a triangle in that plane? (3D)

27 November 2012 - 10:47 AM


In 3D, say you have a triangle defined by three non-aligned points (A,B,C).

How do I find out if the projection of a fourth point onto the plane that the triangle belongs to is inside the triangle?

Dividing large planets

25 June 2012 - 05:31 AM

Hello, I'm trying to make a 3d online game in a sci-fi environment. I've finally got the connection set up, but I'm not shure how I'm going to handle the planets.

I'm planning to make the planets very large to make the game more immersive, leading to the problem that loading something that size into memory at once will probably make something horribly go wrong.

In Minecraft, the worlds are also huge, so they are divided into 16x16 square "chunks" that are loaded when approached by the player and unloaded and saved as he or she moves away from them. I'd like to apply a similar system to my planets, but there's one difference: Minecraft worlds are flat, planets are spherical. How do you divide a sphere into "chunks" without things going crazy around the poles, heightmaps becoming deformed, etc... ?