ChunkUniform.java

public class ChunkUniform {
    private FloatBuffer vertexBuffer;
    private ShortBuffer indexBuffer;
    private FloatBuffer colorBuffer;

    private final int vertCount;

    /**
     * Creates a n*n chunk of uniform-terrain.
     * This implies, that the chunk consists of a closed plane without any cave openings.
     * @param heights An array containing the height map of the chunk. Scaled in Meters. 64 in size.
     */
    public ChunkUniform(float[] heights) {
        //The size of the Chunks sides in Fields. (n)
        final int sizeFields = ((int) Math.sqrt(heights.length)) - 1;
        vertCount = sizeFields * sizeFields * 2 * 3;

        ByteBuffer bb = ByteBuffer.allocateDirect(vertCount * 3 * 4);
        bb.order(ByteOrder.nativeOrder());
        vertexBuffer = bb.asFloatBuffer();

        bb = ByteBuffer.allocateDirect(vertCount * 2);
        bb.order(ByteOrder.nativeOrder());
        indexBuffer = bb.asShortBuffer();

        bb = ByteBuffer.allocateDirect(vertCount * 4 * 4);
        bb.order(ByteOrder.nativeOrder());
        colorBuffer = bb.asFloatBuffer();

        for (int z = 0; z < sizeFields; z++) {
            for (int x = 0; x < sizeFields; x++) {
                //Adds the first face to the square
                putVertex(x,   heights[x     + z     * sizeFields], z  );
                putVertex(x+1, heights[(x+1) + z     * sizeFields], z  );
                putVertex(x,   heights[x     + (z+1) * sizeFields], z+1);

                //Adds the second face to the square
                putVertex(x+1, heights[(x+1) + z     * sizeFields], z  );
                putVertex(x,   heights[x     + (z+1) * sizeFields], z+1);
                putVertex(x+1, heights[(x+1) + (z+1) * sizeFields], z+1);
            }
        }

        for (short i = 0; i < vertCount; i++)
            indexBuffer.put(i);

        //Todo: Fill a color buffer dynamically or according to the chunks surroundings.
        Random r = new Random(0);
        for (int i = 0; i < vertCount / 3; i++) {
            float color[] =  {
                    r.nextFloat(),
                    r.nextFloat(),
                    r.nextFloat(),
                    1.0f
            };
            colorBuffer.put(color);
            colorBuffer.put(color);
            colorBuffer.put(color);

        }

        Log.d("Bellwether", "ChunkUniform: " + vertCount);
    }

    /**
     * Adds a vertex to the vertex buffer.
     * @param x - coordinate in Meters
     * @param y - coordinate in Meters
     * @param z - coordinate in Meters
     */
    private void putVertex(float x, float y, float z) {
        vertexBuffer.put(new float[]{x, y, z});
    }

    /**
     * Draws the chunk. Todo doc this better...
     * @param programHandle The openGL handle of the current rendering program.
     */
    public void draw(final int programHandle) {
        final int positionHandle = GLES20.glGetAttribLocation(programHandle, "vertPos");
        final int colorHandle    = GLES20.glGetAttribLocation(programHandle, "vertColor");

        GLES20.glEnableVertexAttribArray(positionHandle);
        vertexBuffer.rewind();
        GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 12, vertexBuffer);

        GLES20.glEnableVertexAttribArray(colorHandle);
        colorBuffer.rewind();
        GLES20.glVertexAttribPointer(colorHandle, 4, GLES20.GL_FLOAT, false, 16, colorBuffer);

        indexBuffer.rewind();

        GLES20.glDrawElements(GLES20.GL_TRIANGLES, vertCount, GLES20.GL_UNSIGNED_SHORT, indexBuffer);

        GLES20.glDisableVertexAttribArray(positionHandle);
        GLES20.glDisableVertexAttribArray(colorHandle);
    }
}