Untitled

package com.mygdx.game.rendering.GLSLSandbox;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.Texture.TextureFilter;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.glutils.FrameBuffer;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import com.mygdx.game.MyGdxGame;

/**
 * Class that "plays" shaders from the site:
 * http://glslsandbox.com/
 *
 * As a model I used gdx-shadertoy (https://github.com/xoppa/gdx-shadertoy).
 *
 * @author Betalord
 *
 */
public class GLSLSandboxPlayer {

    private SpriteBatch batch;
    private Texture tex1x1;
    private FrameBuffer m_fbo = null; // off screen frame buffer to which we render our shader
    private ShaderProgram shader;
    private float width, height;
    //private OrthographicCamera cam;
    private float time = 0;

    // uniforms
    private int u_time; // "time" uniform
    private int u_cursor; // "mouse" uniform
    private int u_resolution; // "resolution" uniform

    private MyGdxGame game;

    public GLSLSandboxPlayer(MyGdxGame game, String shaderPath, float quality) {
        this.game = game;
        batch = new SpriteBatch();
        /*
        cam = new OrthographicCamera();
        cam.setToOrtho(false, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        cam.update();
        */
        batch.setProjectionMatrix(game.cam.combined);

        Pixmap pixmap = new Pixmap(1, 1, Format.RGBA8888);
        pixmap.drawPixel(0, 0, Color.rgba8888(Color.WHITE));
        tex1x1 = new Texture(pixmap);
        pixmap.dispose();

        shader = loadShader(shaderPath);

        width = Gdx.graphics.getWidth() / quality;
        height = Gdx.graphics.getHeight() / quality;

        // fetch uniforms:
        u_time = shader.fetchUniformLocation("time", false);
        u_cursor = shader.fetchUniformLocation("mouse", false);
        u_resolution = shader.fetchUniformLocation("resolution", false);

        m_fbo = new FrameBuffer(Format.RGBA8888, Math.round(width), Math.round(height), false);
        m_fbo.getColorBufferTexture().setFilter(TextureFilter.Linear, TextureFilter.Linear);
    }

    private void setUniforms() {
        if (u_time >= 0) {
            time += Gdx.graphics.getDeltaTime();
            shader.setUniformf(u_time, time);
        }
        if (u_cursor >= 0) {
            final float cursorX = (float)Gdx.input.getX() / (float)Gdx.graphics.getWidth();
            final float cursorY = 1f - ((float)Gdx.input.getY() / (float)Gdx.graphics.getHeight());
            shader.setUniformf(u_cursor, cursorX, cursorY);
        }
        if (u_resolution >= 0) {
            //***shader.setUniformf(u_resolution, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
            shader.setUniformf(u_resolution, width, height);
        }
    }

    public void render() {
        renderToFBO();

        batch.begin();
        batch.setShader(null);
        batch.draw(m_fbo.getColorBufferTexture(), 0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        batch.end();
    }

    private void renderToFBO() {
        m_fbo.begin(); // binds the frame buffer and sets the viewport accordingly, so everything gets drawn to it.
        Gdx.gl.glViewport(0, 0, Math.round(game.renderer.getWidth()), Math.round(game.renderer.getHeight()));
        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        batch.begin();
        batch.setShader(shader);
        setUniforms();
        batch.draw(tex1x1, 0, 0, width, height);
        batch.end();
        m_fbo.end();
    }

    private ShaderProgram loadShader(String file) {
        ShaderProgram shader = new ShaderProgram(Gdx.files.internal(file + ".vert"), Gdx.files.internal(file + ".frag"));
        if (!shader.isCompiled()) {
            throw new RuntimeException("Error: shader cannot be compiled: " + shader.getLog());
        }
        return shader;
    }

}