GUIElement.class

public class GUIElement {
    public static Matrix4f OrthoMatrix;
    public Shader shader;
    float x1,y1,x2,y2;
    float[] verts;
    float[] texCoords;
    int[] indices;

    int orthoMatrix_loc;
    int modelMatrix_loc;

    int xOffset;
    int yOffset;

    Texture tex;

    VAO vao;

    public GUIElement(Texture tex, int x, int y) {
        this.tex=tex;

        float width;
        float height;

        width = tex.getImageWidth();
        height = tex.getImageHeight();

        x1 = 0;
        y1 = 0;
        x2 = width;
        y2 = height;

        xOffset = x;
        yOffset = y;

        verts = new float[] {
            x2,y1,0f,
            x2,y2,0f,
            x1,y2,0f,
            x1,y1,0f
        };

        indices = new int[] {
            0, 1, 3,
            3, 1, 2
        };

        texCoords = new float[] {
            0, 1,
            1, 1,
            1, 0,
            0, 0
        };

        vao = new VAO(verts, new float[]{}, texCoords, indices);

        shader = new Shader("guiShader") {
            @Override
            protected void bindAttributes() {
                bindAttribute(0, "position");
                bindAttribute(2, "texCoord");
            }
            @Override
            protected void getAllUniformLocations() {
                orthoMatrix_loc = getUniformLocation("orthoMatrix");
                modelMatrix_loc = getUniformLocation("modelMatrix");
            }
        };

        shader.start();
            shader.loadMatrix(orthoMatrix_loc, OrthoMatrix);
        shader.stop();

        System.out.println(String.format("%1f %2f %3f %4f", x1+xOffset,y1+yOffset,x2,y2));
    }

    public void draw() {
        glBindVertexArray(vao.getVaoID());
        GL20.glEnableVertexAttribArray(0);
        GL20.glEnableVertexAttribArray(2);
        shader.start();
        shader.loadMatrix(modelMatrix_loc, Util.createTransformationMatrix(new Vector3f(xOffset,yOffset,0),0,0,0,1));
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, tex.getTextureID());
        glDisable(GL_CULL_FACE);
        glDisable(GL_DEPTH_TEST);
        glDrawElements(GL_TRIANGLES, indices.length, GL_UNSIGNED_INT, 0);
        glActiveTexture(0);
        glBindTexture(GL_TEXTURE_2D, 0);
        glEnable(GL_CULL_FACE);
        glEnable(GL_DEPTH_TEST);
        shader.stop();
        GL20.glDisableVertexAttribArray(0);
        GL20.glDisableVertexAttribArray(2);
        glBindVertexArray(0);
    }

    public static void createOrtho() {
        OrthoMatrix = new Matrix4f();
        OrthoMatrix.setIdentity();

        float zNear = 1;
        float zFar = -1;
        float m00 = 2 / (Display.getWidth());
        float m11 = 2 / (Display.getHeight());
        float m22 = -2 / (zFar-zNear);
        float m23 = -(zFar+zNear)/(zFar-zNear);
        float m33 = 1;

        OrthoMatrix.m00 = m00;
        OrthoMatrix.m11 = m11;
        OrthoMatrix.m22 = m22;
        OrthoMatrix.m23 = m23;
        OrthoMatrix.m33 = m33;
    }
}