Shape2D class

package primitives;

import java.nio.FloatBuffer;
import java.util.Arrays;

import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.GL11;
import org.lwjgl.util.vector.Matrix2f;
import org.lwjgl.util.vector.Vector2f;

public class Shape2D
{
    protected float xPos;
    protected float yPos;

    protected float[] localVerts;
    protected float[] absoluteVerts;
    protected float[] texCoords = null;
    protected float[] colors = null;


    protected float rotation;


    public void draw(int glMode)
    {
        GL11.glBegin(glMode);

        for (int i = 0; i < absoluteVerts.length / 2; i += 2)
        {
            if (colors == null)
                GL11.glTexCoord2f(texCoords[i * 2], texCoords[i * 2 + 1]);
            else
                GL11.glColor3f(colors[i * 3], colors[i * 3 + 1], colors[i * 3 + 2]);
            GL11.glVertex2f(absoluteVerts[i * 2], absoluteVerts[i * 2 + 1]);
        }

        GL11.glEnd();
    }

    public void drawWithModeBegun()
    {
        for (int i = 0; i < absoluteVerts.length / 2; i += 2)
        {
            if (colors == null)
                GL11.glTexCoord2f(texCoords[i * 2], texCoords[i * 2 + 1]);
            else
                GL11.glColor3f(colors[i * 3], colors[i * 3 + 1], colors[i * 3 + 2]);
            GL11.glVertex2f(absoluteVerts[i * 2], absoluteVerts[i * 2 + 1]);
        }
    }


    public void updateAbsoluteVerticies()
    {
        absoluteVerts = new float[localVerts.length];

        for (int i = 0; i < localVerts.length; i += 2)
        {
            absoluteVerts[i] = xPos + localVerts[i];
            absoluteVerts[i + 1] = yPos + localVerts[i + 1];
        }
    }

    public void setPosition(float newX, float newY)
    {
        xPos = newX;
        yPos = newY;
    }

    public float getXPos()
    {
        return xPos;
    }

    public float getYPos()
    {
        return yPos;
    }

    public void setScale(float xScale, float yScale)
    {
        Matrix2f trans = getScaleMatrix(xScale, yScale);

        for (int i = 0; i < localVerts.length; i += 2)
        {
            Vector2f vec = new Vector2f(localVerts[i], localVerts[i + 1]);
            Vector2f result = Matrix2f.transform(trans, vec, null);
            localVerts[i] = result.x;
            localVerts[i + 1] = result.y;
        }
    }

    public void setRotation(float rotation)
    {
        Matrix2f trans = getRotationMatrix(rotation - this.rotation);

        for (int i = 0; i < localVerts.length; i += 2)
        {
            Vector2f vec = new Vector2f(localVerts[i], localVerts[i + 1]);
            Vector2f result = Matrix2f.transform(trans, vec, null);
            localVerts[i] = result.x;
            localVerts[i + 1] = result.y;
        }
        this.rotation = rotation;
    }

    public void rotate(float rotationChange)
    {
        Matrix2f trans = getRotationMatrix(rotationChange);

        for (int i = 0; i < localVerts.length; i += 2)
        {
            Vector2f vec = new Vector2f(localVerts[i], localVerts[i + 1]);
            Vector2f result = Matrix2f.transform(trans, vec, null);
            localVerts[i] = result.x;
            localVerts[i + 1] = result.y;
        }
        this.rotation += rotationChange;
    }


    private Matrix2f getRotationMatrix(float rotation)
    {
        float cos = (float)Math.cos(rotation);
        float sin = (float)Math.sin(rotation);

        float[] array = {
                cos, -sin,
                sin, cos
        };

        FloatBuffer buf = BufferUtils.createFloatBuffer(array.length);
        buf.put(array);
        buf.flip();

        Matrix2f result = new Matrix2f();
        result.load(buf);

        return result;
    }

    private Matrix2f getScaleMatrix(float xScale, float yScale)
    {
        float[] array = {
                xScale, 0,
                0,      yScale
        };

        FloatBuffer buf = BufferUtils.createFloatBuffer(array.length);
        buf.put(array);
        buf.flip();

        Matrix2f result = new Matrix2f();
        result.load(buf);

        return result;
    }
}