snuvi-engine/src/me/hammerle/snuviengine/api/Texture.java

package me.hammerle.snuviengine.api;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.IntBuffer;
import javax.imageio.ImageIO;
import org.lwjgl.BufferUtils;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL12.*;
import static org.lwjgl.opengl.GL13.*;

public class Texture {
    public class Animation {
        private final IntBuffer[] data;
        private final int[] widths;
        private final int[] heights;
        private final int offsetX;
        private final int offsetY;
        private int index = 0;

        private Animation(int offsetX, int offsetY, String... paths) {
            this.offsetX = offsetX;
            this.offsetY = offsetY;
            int l = paths.length;
            data = new IntBuffer[l];
            widths = new int[l];
            heights = new int[l];

            for(int i = 0; i < l; i++) {
                BufferedImage image = readImage(paths[i], false);
                if(offsetX + image.getWidth() > width || offsetY + image.getHeight() > height) {
                    System.out.println(String.format("animation image '%s'is out of range", paths[i]));
                    return;
                }
                widths[i] = image.getWidth();
                heights[i] = image.getHeight();
                data[i] = createBufferFromImage(image);
            }
        }

        public void nextFrame() {
            glActiveTexture(GL_TEXTURE0);
            glTexSubImage2D(GL_TEXTURE_2D, 0, offsetX, offsetY, widths[index], heights[index], GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, data[index]);
            index = (index + 1) % data.length;
        }
    }

    private static BufferedImage readImage(String path, boolean internal) {
        try {
            if(internal) {
                return ImageIO.read(Texture.class.getClassLoader().getResource("me/hammerle/snuviengine/resources/" + path));
            }
            return ImageIO.read(new File(path));
        } catch(IOException | IllegalArgumentException ex) {
            System.out.println(String.format("cannot read texture file '%s': %s", path, ex.getMessage()));
            return new BufferedImage(0, 0, BufferedImage.TYPE_INT_ARGB);
        }
    }

    private static IntBuffer createBufferFromImage(BufferedImage image) {
        IntBuffer buffer = BufferUtils.createIntBuffer(image.getWidth() * image.getHeight());
        for(int y = 0; y < image.getHeight(); y++) {
            for(int x = 0; x < image.getWidth(); x++) {
                int c = image.getRGB(x, y);
                buffer.put((c << 8) | ((c >> 24) & 0xFF));
            }
        }
        buffer.flip();
        return buffer;
    }

    private static int boundTexture = -1;
    private final int texture;
    private final int width;
    private final int height;

    protected Texture(String path, boolean internal) {
        BufferedImage image = readImage(path, internal);
        IntBuffer buffer = createBufferFromImage(image);
        width = image.getWidth();
        height = image.getHeight();
        glActiveTexture(GL_TEXTURE0);
        texture = glGenTextures();
        glBindTexture(GL_TEXTURE_2D, texture);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, buffer);
    }

    public Texture(String path) {
        this(path, false);
    }

    public Animation addAnimation(int offsetX, int offsetY, String... paths) {
        return new Animation(offsetX, offsetY, paths);
    }

    public void bind() {
        if(boundTexture != texture) {
            boundTexture = texture;
            glBindTexture(GL_TEXTURE_2D, texture);
        }
    }
}