game.engine.frame.handlers.FpsPanel.java Source code

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Here is the source code for game.engine.frame.handlers.FpsPanel.java

Source

/**
 * Copyright (c) 2012 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package game.engine.frame.handlers;

import static org.lwjgl.opengl.GL11.GL_BLEND;
import static org.lwjgl.opengl.GL11.GL_ONE_MINUS_SRC_ALPHA;
import static org.lwjgl.opengl.GL11.GL_SRC_ALPHA;
import static org.lwjgl.opengl.GL11.GL_TEXTURE_2D;
import static org.lwjgl.opengl.GL11.glBindTexture;
import static org.lwjgl.opengl.GL11.glBlendFunc;
import static org.lwjgl.opengl.GL11.glEnable;
import static org.lwjgl.opengl.GL14.glWindowPos2i;
import game.engine.frame.AbstractFrameHandler;
import game.engine.gfx.Font;

import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.GL11;

/**
 * Displays the current frames per second on the screen.
 */
public final class FpsPanel extends AbstractFrameHandler {

    /**
     * the font
     */
    private final Font font;

    /**
     * the lastSamplingTime
     */
    private long lastSamplingTime;

    /**
     * the countedFrames
     */
    private int countedFrames;

    /**
     * the fps
     */
    private int fps;

    /**
     * Constructor.
     * @param font the font used to draw text
     */
    public FpsPanel(Font font) {
        this.font = font;
        this.lastSamplingTime = System.currentTimeMillis();
        this.countedFrames = 0;
        this.fps = 0;
    }

    /* (non-Javadoc)
     * @see game.engine.frame.AbstractFrameHandler#draw()
     */
    @Override
    public void draw() {

        // update FPS
        countedFrames++;
        long now = System.currentTimeMillis();
        if ((now - lastSamplingTime) >= 1000) {
            fps = countedFrames;
            countedFrames = 0;
            lastSamplingTime = now;
        }

        // draw the FPS panel
        String fpsText = Float.toString(fps);
        glBindTexture(GL_TEXTURE_2D, 0);
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        glWindowPos2i(Display.getWidth(), Display.getHeight());
        GL11.glPixelTransferf(GL11.GL_RED_BIAS, 1.0f);
        GL11.glPixelTransferf(GL11.GL_GREEN_BIAS, 1.0f);
        GL11.glPixelTransferf(GL11.GL_BLUE_BIAS, 1.0f);
        font.drawText(fpsText, 2, Font.ALIGN_RIGHT, Font.ALIGN_TOP);
        GL11.glPixelTransferf(GL11.GL_RED_BIAS, 0.0f);
        GL11.glPixelTransferf(GL11.GL_GREEN_BIAS, 0.0f);
        GL11.glPixelTransferf(GL11.GL_BLUE_BIAS, 0.0f);

    }

}