drawing coloured rectangle

Test.java

@@ -1,20 +1,21 @@
-import com.danitheskunk.skunkworks.Engine;
-import com.danitheskunk.skunkworks.GLWindow;
-import com.danitheskunk.skunkworks.Vec2f;
-import com.danitheskunk.skunkworks.Vec2i;
+import com.danitheskunk.skunkworks.*;
 
 public class Test {
 	public static void main(String[] args) {
 		var engine = new Engine();
 		var window = engine.openWindow(1280, 720, "Skunkworks");
-		var window2 = engine.openWindow(1280, 720, "Skunkworks");
 		var img = engine.loadImage("C:\\Users\\dani\\Videos\\Screenshot 2022-06-25 17-00-59.png");
 		//var img = engine.loadImage("C:\\art\\kyoko.png");
 		System.out.println(img.getPixel(new Vec2i(60, 60)));
 
 		while(!window.shouldClose()) {
 			window.tick();
-			window2.tick();
+			var renderContext = window.renderStart();
+			renderContext.drawRectangle(
+				new Recti(100, 100, 100, 100),
+				new Color(150, 200, 250)
+			);
+			window.renderFinish(renderContext);
 		}
 	}
 }

com/danitheskunk/skunkworks/GLRenderContext.java

@@ -0,0 +1,29 @@
+package com.danitheskunk.skunkworks;
+
+import static org.lwjgl.opengl.GL11.*;
+
+public class GLRenderContext implements IRenderContext{
+	@Override
+	public void drawRectangle(Recti rect, Color color) {
+		var tl = rect.getTopLeft();
+		var tr = rect.getTopRight();
+		var bl = rect.getBottomLeft();
+		var br = rect.getBottomRight();
+
+		glColor4f(
+			color.getR() / 255.0f,
+			color.getG() / 255.0f,
+			color.getB() / 255.0f,
+			color.getA() / 255.0f
+		);
+
+		//counter clockwise triangles
+		glVertex2i(bl.getX(), bl.getY());
+		glVertex2i(tr.getX(), tr.getY());
+		glVertex2i(tl.getX(), tl.getY());
+
+		glVertex2i(tr.getX(), tr.getY());
+		glVertex2i(bl.getX(), bl.getY());
+		glVertex2i(br.getX(), bl.getY());
+	}
+}

com/danitheskunk/skunkworks/GLWindow.java

@@ -10,26 +10,30 @@ import static org.lwjgl.opengl.GL11.*;
 import static org.lwjgl.system.MemoryUtil.NULL;
 
 public class GLWindow implements IWindow {
-	private long window;
+	private GLRenderContext renderContext;
 	private boolean shouldClose;
+	private long window;
 
 	public GLWindow(int width, int height, String title) {
 		GLFWErrorCallback.createPrint(System.err).set();
-		if (!glfwInit())
-			throw new IllegalStateException("Unable to initialize GLFW");
+		if(!glfwInit()) throw new IllegalStateException("Unable to initialize GLFW");
 
 		glfwDefaultWindowHints();
 
 		window = glfwCreateWindow(width, height, title, NULL, NULL);
-		if (window == NULL)
-			throw new RuntimeException("Failed to create GLFW window");
+		if(window == NULL) throw new RuntimeException("Failed to create GLFW window");
 
-		glfwMakeContextCurrent(window);
-		glfwSwapInterval(1); //vsync
 
 		glfwShowWindow(window);
-
+		glfwMakeContextCurrent(window);
+		glfwSwapInterval(1); //vsync
 		GL.createCapabilities();
+		glMatrixMode(GL_PROJECTION);
+		glLoadIdentity();
+		glOrtho(0.0f, width, height, 0.0f, 0.0f, 1.0f);
+		glEnable(GL_COLOR);
+
+		renderContext = new GLRenderContext();
 
 		shouldClose = false;
 
@@ -38,6 +42,20 @@ public class GLWindow implements IWindow {
 		System.out.println(GL11.glGetInteger(GL_MAX_TEXTURE_SIZE));
 	}
 
+	@Override
+	public void renderFinish(IRenderContext context) {
+		glEnd();
+		glfwSwapBuffers(window);
+	}
+
+	@Override
+	public IRenderContext renderStart() {
+		glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		glBegin(GL_TRIANGLES);
+		return renderContext;
+	}
+
 	@Override
 	public boolean shouldClose() {
 		return shouldClose;
@@ -45,14 +63,12 @@ public class GLWindow implements IWindow {
 
 	@Override
 	public void tick() {
+		glfwMakeContextCurrent(window);
 		if(glfwWindowShouldClose(window)) {
 			shouldClose = true;
 			return;
 		}
 
-		glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
-		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-		glfwSwapBuffers(window);
 		glfwPollEvents();
 	}
 }

com/danitheskunk/skunkworks/IWindow.java

@@ -1,6 +1,8 @@
 package com.danitheskunk.skunkworks;
 
 public interface IWindow {
+	void renderFinish(IRenderContext context);
+	IRenderContext renderStart();
 	boolean shouldClose();
 	void tick();
 }