com.sturdyhelmetgames.dodgethecars.screen.BasicScreen.java Source code

Introduction

Here is the source code for com.sturdyhelmetgames.dodgethecars.screen.BasicScreen.java

Source

/*
 * Copyright 2012 Antti Kolehmainen
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.sturdyhelmetgames.dodgethecars.screen;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.InputAdapter;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.math.Matrix4;
import com.sturdyhelmetgames.dodgethecars.DodgeTheCarsGame;
import com.sturdyhelmetgames.dodgethecars.assets.Art;

/**
 * Basic stuff needed by all game screens.
 * 
 * @author Antti 18.6.2012
 * 
 */
public abstract class BasicScreen extends InputAdapter implements Screen {

    public DodgeTheCarsGame game;
    protected final OrthographicCamera camera = new OrthographicCamera(48, 32);
    protected final SpriteBatch spriteBatch = new SpriteBatch();
    protected final Matrix4 normalProjection = new Matrix4();
    protected boolean isGL20Available = false;
    protected boolean stepped = false;

    private static final int MAX_FPS = 60;
    private static final int MIN_FPS = 15;
    private static final float TIME_STEP = 1f / MAX_FPS;
    private static final float MAX_STEPS = 1f + MAX_FPS / MIN_FPS;
    private static final float MAX_TIME_PER_FRAME = TIME_STEP * MAX_STEPS;
    private float stepTimeLeft;

    public BasicScreen(DodgeTheCarsGame game) {
        this.game = game;

        // check if gl2 is available
        isGL20Available = Gdx.graphics.isGL20Available();

        // reset camera
        camera.position.set(0, 0, 0);
        camera.update();

        // set a normal projection matrix
        normalProjection.setToOrtho2D(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    }

    /**
     * Does a fixed timestep independently of framerate.
     * 
     * @param delta
     *            Delta time.
     * @return True if stepped, false otherwise.
     */
    private void fixedStep(float delta) {
        stepTimeLeft += delta;
        if (stepTimeLeft > MAX_TIME_PER_FRAME)
            stepTimeLeft = MAX_TIME_PER_FRAME;
        while (stepTimeLeft >= TIME_STEP) {
            updateScreen(TIME_STEP);
            stepTimeLeft -= TIME_STEP;
        }
    }

    /**
     * Updates the game logic.
     * 
     * @param fixedStep
     *            A fixed timestep.
     */
    protected abstract void updateScreen(float fixedStep);

    /**
     * Renders the game graphics.
     * 
     * @param delta
     *            Delta time.
     */
    public abstract void renderScreen(float delta);

    @Override
    public void render(float delta) {

        fixedStep(delta);

        if (isGL20Available) {
            Gdx.graphics.getGL20().glClear(GL20.GL_COLOR_BUFFER_BIT);
        } else {
            Gdx.graphics.getGL10().glClear(GL10.GL_COLOR_BUFFER_BIT);
        }

        // render screen graphics
        renderScreen(delta);

        // render fps if in debug mode
        if (isDebug()) {
            spriteBatch.getProjectionMatrix().set(normalProjection);
            spriteBatch.begin();
            Art.debugFont.draw(spriteBatch, "FPS: " + Gdx.graphics.getFramesPerSecond(), 0, 20);
            spriteBatch.end();
        }
    }

    @Override
    public void dispose() {
        spriteBatch.dispose();
    }

    /**
     * Is the screen in DEBUG mode?
     * 
     * @return If screen is in DEBUG mode returns true, otherwise returns false.
     */
    protected boolean isDebug() {
        return DodgeTheCarsGame.DEBUG;
    }

    @Override
    public void show() {

    }

    @Override
    public void hide() {

    }

    @Override
    public void pause() {

    }

    @Override
    public void resume() {

    }

    @Override
    public void resize(int width, int height) {

    }

}