Now a triangle in the config screen (until you resize the window, then it crashes)

src/main/java/com/seibel/lod/core/config/gui/ConfigScreen.java

@@ -1,17 +1,99 @@
 package com.seibel.lod.core.config.gui;
 
+import com.seibel.lod.core.enums.config.GpuUploadMethod;
+import com.seibel.lod.core.render.GLProxy;
+import com.seibel.lod.core.render.objects.GLState;
+import com.seibel.lod.core.render.objects.GLVertexBuffer;
+import com.seibel.lod.core.render.objects.ShaderProgram;
+import com.seibel.lod.core.render.objects.VertexAttribute;
+import org.lwjgl.opengl.GL32;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
 /**
  * @author coolGi
  */
 public class ConfigScreen extends AbstractScreen {
+    ShaderProgram basicShader;
+    GLVertexBuffer sameContextBuffer;
+    GLVertexBuffer sharedContextBuffer;
+    VertexAttribute va;
+
+    private static final float[] vertices = {
+            // PosX,Y, ColorR,G,B,A
+            -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f,
+            0.4f, -0.4f, 1.0f, 0.0f, 0.0f, 1.0f,
+            0.3f, 0.3f, 1.0f, 1.0f, 0.0f, 0.0f,
+            -0.2f, 0.2f, 0.0f, 1.0f, 1.0f, 1.0f
+    };
+
     @Override
     public void init() {
         System.out.println("init");
+
+        va = VertexAttribute.create();
+        va.bind();
+        // Pos
+        va.setVertexAttribute(0, 0, VertexAttribute.VertexPointer.addVec2Pointer(false));
+        // Color
+        va.setVertexAttribute(0, 1, VertexAttribute.VertexPointer.addVec4Pointer(false));
+        va.completeAndCheck(Float.BYTES * 6);
+        basicShader = new ShaderProgram("shaders/test/vert.vert", "shaders/test/frag.frag",
+                "fragColor", new String[]{"vPosition", "color"});
+        createBuffer();
+    }
+
+    private void createBuffer() {
+        GLProxy.getInstance().recordOpenGlCall(() -> sharedContextBuffer = createTextingBuffer());
+        GLProxy.ensureAllGLJobCompleted();
+        sameContextBuffer = createTextingBuffer();
+    }
+
+    private static GLVertexBuffer createTextingBuffer() {
+        ByteBuffer buffer = ByteBuffer.allocateDirect(vertices.length * Float.BYTES);
+        // Fill buffer with the vertices.
+        buffer = buffer.order(ByteOrder.nativeOrder());
+        buffer.asFloatBuffer().put(vertices);
+        buffer.rewind();
+        GLVertexBuffer vbo = new GLVertexBuffer(false);
+        vbo.bind();
+        vbo.uploadBuffer(buffer, 4, GpuUploadMethod.DATA, vertices.length * Float.BYTES);
+        return vbo;
     }
 
     @Override
     public void render(float delta) {
         System.out.println("Updated config screen with the delta of " + delta);
+
+        GLState state = new GLState();
+        init();
+//        GL32.glBindFramebuffer(GL32.GL_FRAMEBUFFER, GL32.GL_FRAMEBUFFER_BINDING);
+        GL32.glViewport(0,0, width, height);
+        GL32.glPolygonMode(GL32.GL_FRONT_AND_BACK, GL32.GL_FILL);
+//        GL32.glDisable(GL32.GL_3D); // TODO: Disable 3d for the config as we dont need it
+        GL32.glDisable(GL32.GL_CULL_FACE);
+        GL32.glDisable(GL32.GL_DEPTH_TEST);
+        GL32.glDisable(GL32.GL_STENCIL_TEST);
+        GL32.glDisable(GL32.GL_BLEND);
+//        GL32.glDisable(GL32.GL_SCISSOR_TEST);
+
+        basicShader.bind();
+        va.bind();
+
+        // Switch between the two buffers per second
+        if (System.currentTimeMillis() % 2000 < 1000) {
+            sameContextBuffer.bind();
+            va.bindBufferToAllBindingPoint(sameContextBuffer.getId());
+        } else {
+            sameContextBuffer.bind();
+            va.bindBufferToAllBindingPoint(sharedContextBuffer.getId());
+        }
+        // Render the square
+        GL32.glDrawArrays(GL32.GL_TRIANGLE_FAN, 0, 4);
+        GL32.glClear(GL32.GL_DEPTH_BUFFER_BIT);
+
+        state.restore();
     }
 
     @Override