implemented texture atlas

Test.java

@@ -4,10 +4,11 @@ public class Test {
 	public static void main(String[] args) {
 		var engine = new Engine();
 		var window = engine.openWindow(1280, 720, "Skunkworks");
+		var img2 = engine.loadImage("C:\\art\\pixel stuff.png");
 		var img = engine.loadImage("C:\\Users\\dani\\Videos\\Screenshot 2022-06-25 17-00-59.png");
-		//var img = engine.loadImage("C:\\art\\kyoko.png");
+		var tex2 = window.loadTexture("C:\\art\\pixel stuff.png");
-		var tex = window.loadTexture("C:\\Users\\dani\\Videos\\Screenshot 2022-06-25 17-00-59.png");
+		//img.drawImage(img2, Vec2i.ZERO);
-		System.out.println(img.getPixel(new Vec2i(60, 60)));
+		var tex = window.loadTexture(img);
 
 		while(!window.shouldClose()) {
 			window.tick();
@@ -17,9 +18,13 @@ public class Test {
 			//	new Color(150, 200, 250)
 			//);
 			renderContext.drawTextureRectangle(
-				new Recti(100, 100, 100, 100),
+				new Recti(0, 0, 1280, 720),
 				tex
 			);
+			renderContext.drawTextureRectangle(
+				new Recti(new Vec2i(200, 100), tex2.getSize()),
+				tex2
+			);
 			window.renderFinish(renderContext);
 		}
 	}

com/danitheskunk/skunkworks/GLRenderContext.java

@@ -3,6 +3,11 @@ package com.danitheskunk.skunkworks;
 import static org.lwjgl.opengl.GL11.*;
 
 public class GLRenderContext implements IRenderContext{
+	private GLTextureAtlas atlas;
+
+	public GLRenderContext(GLTextureAtlas atlas) {
+		this.atlas = atlas;
+	}
 	@Override
 	public void drawRectangle(Recti rect, Color color) {
 		var tl = rect.getTopLeft();
@@ -36,11 +41,18 @@ public class GLRenderContext implements IRenderContext{
 
 	@Override
 	public void drawTextureRectangle(Recti rect, ITexture texture, Color color) {
+		var tex = (GLTexture)texture;
+
 		var tl = rect.getTopLeft();
 		var tr = rect.getTopRight();
 		var bl = rect.getBottomLeft();
 		var br = rect.getBottomRight();
 
+		var ttl = Vec2i.divf(tex.getTexArea().getTopLeft(),     atlas.getSize());
+		var ttr = Vec2i.divf(tex.getTexArea().getTopRight(),    atlas.getSize());
+		var tbl = Vec2i.divf(tex.getTexArea().getBottomLeft(),  atlas.getSize());
+		var tbr = Vec2i.divf(tex.getTexArea().getBottomRight(), atlas.getSize());
+
 		glColor4f(
 			color.getR() / 255.0f,
 			color.getG() / 255.0f,
@@ -49,18 +61,18 @@ public class GLRenderContext implements IRenderContext{
 		);
 
 		//counter clockwise triangles
-		glTexCoord2f(0.0f, 1.0f);
+		glTexCoord2d(tbl.getX(), tbl.getY());
 		glVertex2i(bl.getX(), bl.getY());
-		glTexCoord2f(1.0f, 0.0f);
+		glTexCoord2d(ttr.getX(), ttr.getY());
 		glVertex2i(tr.getX(), tr.getY());
-		glTexCoord2f(0.0f, 0.0f);
+		glTexCoord2d(ttl.getX(), ttl.getY());
 		glVertex2i(tl.getX(), tl.getY());
 
-		glTexCoord2f(1.0f, 0.0f);
+		glTexCoord2d(ttr.getX(), ttr.getY());
 		glVertex2i(tr.getX(), tr.getY());
-		glTexCoord2f(0.0f, 1.0f);
+		glTexCoord2d(tbl.getX(), tbl.getY());
 		glVertex2i(bl.getX(), bl.getY());
-		glTexCoord2f(1.0f, 1.0f);
+		glTexCoord2d(tbr.getX(), tbr.getY());
 		glVertex2i(br.getX(), bl.getY());
 	}
 }

com/danitheskunk/skunkworks/GLTexture.java

@@ -2,13 +2,22 @@ package com.danitheskunk.skunkworks;
 
 public class GLTexture implements ITexture {
 	private Recti texArea;
+	Image img; //for re-blitting onto texture atlas
 
-	GLTexture(Recti texArea) {
+	GLTexture(Recti texArea, Image img) {
 		this.texArea = texArea;
+		this.img = img;
 	}
 
 	//setters
+	@Override
+	public Vec2i getSize() { return this.img.getSize(); }
 	void setTexArea(Recti texArea) {
 		this.texArea = texArea;
 	}
+
+
+	public Recti getTexArea() {
+		return texArea;
+	}
 }

com/danitheskunk/skunkworks/GLTextureAtlas.java

@@ -1,9 +1,12 @@
 package com.danitheskunk.skunkworks;
 
 import org.lwjgl.BufferUtils;
+import org.lwjgl.stb.STBRPContext;
+import org.lwjgl.stb.STBRectPack;
 
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 
 import static org.lwjgl.opengl.GL11.*;
@@ -26,14 +29,63 @@ class GLTextureAtlas {
 
 	ITexture addTexture(Image img) {
 		//todo: do the actual texture stuff
-		this.img = img;
+		//this.img = img;
-		update();
+		var texture = new GLTexture(new Recti(new Vec2i(0, 0), img.getSize()), img);
-		var texture = new GLTexture(new Recti(new Vec2i(0, 0), img.getSize()));
 		textures.add(texture);
+		repack();
+		updateImage();
+		uploadToGpu();
 		return texture;
 	}
 
-	void update() {
+	void doubleAtlasSize() {
+		img = new Image(Vec2i.mul(img.getSize(), 2));
+		System.out.printf("Resized atlas to %dx%d\n", img.getSize().getX(), img.getSize().getY());
+	}
+
+	void repack() {
+		int x = 0;
+		int y = 0;
+		int height;
+
+		textures.sort(new TextureHeightComparator().reversed());
+		height = textures.get(0).img.getHeight();
+
+		for(var tex : textures) {
+			//texture larger than atlas? resize atlas and try again
+			if(tex.img.getHeight() > img.getHeight() || tex.img.getWidth() > img.getWidth()) {
+				doubleAtlasSize();
+				repack();
+				return;
+			}
+
+			//row full? start the next row
+			if(img.getWidth() - x < tex.img.getWidth()) {
+				x = 0;
+				y += height;
+				height = tex.img.getHeight();
+
+				//not enough space for new row? resize atlas and try again
+				if(y + height > tex.img.getHeight()) {
+					doubleAtlasSize();
+					repack();
+					return;
+				}
+			}
+
+			//take space, advance to right
+			tex.setTexArea(new Recti(new Vec2i(x, y), tex.img.getSize()));
+			x += tex.img.getWidth();
+		}
+	}
+
+	void updateImage() {
+		for(var tex : textures) {
+			img.drawImage(tex.img, tex.getTexArea().getPos());
+		}
+	}
+
+	void uploadToGpu() {
 		var buf = BufferUtils.createByteBuffer(img.getData().length);
 		buf.put(img.getData());
 		buf.flip();
@@ -50,4 +102,16 @@ class GLTextureAtlas {
 			buf
 		);
 	}
+
+	public Vec2i getSize() {
+		return img.getSize();
 	}
+
+	private class TextureHeightComparator implements Comparator<GLTexture> {
+		@Override
+		public int compare(GLTexture o1, GLTexture o2) {
+			return o1.img.getHeight() - o2.img.getHeight();
+		}
+	}
+}
+

com/danitheskunk/skunkworks/GLWindow.java

@@ -38,8 +38,8 @@ public class GLWindow implements IWindow {
 		glEnable(GL_COLOR);
 		glEnable(GL_TEXTURE_2D);
 
-		renderContext = new GLRenderContext();
 		textureAtlas = new GLTextureAtlas();
+		renderContext = new GLRenderContext(textureAtlas);
 
 		shouldClose = false;
 

com/danitheskunk/skunkworks/ITexture.java

@@ -1,5 +1,5 @@
 package com.danitheskunk.skunkworks;
 
 public interface ITexture {
-
+	Vec2i getSize();
 }

com/danitheskunk/skunkworks/Vec2i.java

@@ -43,8 +43,26 @@ public final class Vec2i {
 	public static Vec2i mul(Vec2i a, int b) {
 		return new Vec2i(a.x * b, a.y * b);
 	}
+	public static Vec2i mul(Vec2i a, Vec2i b) {
+		return new Vec2i(a.x * b.x, a.y * b.y);
+	}
 
 	public static Vec2i div(Vec2i a, int b) {
 		return new Vec2i(a.x / b, a.y / b);
 	}
+	public static Vec2i div(Vec2i a, Vec2i b) {
+		return new Vec2i(a.x / b.x, a.y / b.y);
+	}
+	public static Vec2f divf(Vec2i a, double b) {
+		return new Vec2f(a.x / b, a.y / b);
+	}
+	public static Vec2f divf(Vec2i a, Vec2f b) {
+		return new Vec2f(a.x / b.x, a.y / b.y);
+	}
+	public static Vec2f divf(Vec2i a, int b) {
+		return new Vec2f(a.x / (double)b, a.y / (double)b);
+	}
+	public static Vec2f divf(Vec2i a, Vec2i b) {
+		return new Vec2f(a.x / (double)b.x, a.y / (double)b.y);
+	}
 }