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POBlended textures show up fine, but ordinary coloured shapes do not
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  1. POBlended textures show up fine, but ordinary coloured shapes do not
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    copied!<p>For some reason enabling alpha blending results in me not being able to draw run-of-the-mill coloured shapes. The order in which everything is drawn makes no difference. Even if the only thing being drawn is the coloured shape, it still won't show.</p> <p>Disabling alpha blending fixes this, but disables alpha blending (obviously). This leads me to believe the problem is in how I'm initializing openGL.</p> <p>The textured objects are contained in the world, which is commented out. Commenting "world.run();" out makes no difference, only disabling alpha blending does.</p> <pre><code>public class Core { int width=800, height=600; //World world; public void Start(){ try { Display.setDisplayMode(new DisplayMode(width,height)); Display.create(); } catch (LWJGLException e) { e.printStackTrace(); System.exit(0); } initGL(); System.out.println("OpenGL version: " + GL11.glGetString(GL11.GL_VERSION)); boolean Close = Display.isCloseRequested(); //world = new World(width, height); while(!Close){ GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); if(Keyboard.isKeyDown(Keyboard.KEY_ESCAPE) || Display.isCloseRequested()) Close = true; //world.run(); GL11.glColor4d(1, 0, 0, 1); GL11.glBegin(GL11.GL_QUADS); GL11.glVertex2d(0, 0); GL11.glVertex2d(0, 50); GL11.glVertex2d(50, 50); GL11.glVertex2d(50, 0); GL11.glEnd(); Display.update(); //Display.sync(60); } } public void initGL(){ GL11.glEnable(GL11.GL_TEXTURE_2D); GL11.glClearColor(1.0f, 1.0f, 1.0f, 0.0f); // enable alpha blending GL11.glEnable(GL11.GL_BLEND); GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA); GL11.glViewport(0,0,width,height); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); GL11.glOrtho(0, width, height, 0, 1, -1); GL11.glMatrixMode(GL11.GL_MODELVIEW); } public static void main(String args[]){ Core m = new Core(); m.Start(); } </code></pre> <p>}</p> <p>This is for a 2D app where I'm trying to draw metaballs behind the texture of a black-and-white world map.</p> <p>Run-of-the-mill coloured shapes refers to the following,</p> <pre><code>GL11.glColor4d(1, 0, 0, 1); GL11.glBegin(GL11.GL_QUADS); GL11.glVertex2d(0, 0); GL11.glVertex2d(0, 50); GL11.glVertex2d(50, 50); GL11.glVertex2d(50, 0); GL11.glEnd(); </code></pre> <p>Even if drawn on its own, as long as alpha blending is enabled, it won't show up.</p> <p>UPDATE: The constructor for <em>world</em> was loading (but not drawing) a texture. Removing that part of the code lets the coloured square show up. I have deduced that the problem will occur as long as a texture is loaded, regardless of whether it is displayed or not.</p>
 

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