CODEWITHSUNDEEP
javaopengllwjgl
Trey
Trey

Reputation: 3

Java - Binding texture in LWJGL causes white screen

Recently I've been trying to implement my own PNG texture decoder/loader, however like my several previous attempts the outcome is the same... no textures. Here is the code (Not mine! I forget the website) I currently use for loading the image:

public static TextureObject loadTexture(BufferedImage image)
             {
             int[] pixels = new int[image.getWidth() * image.getHeight()];
                image.getRGB(0, 0, image.getWidth(), image.getHeight(), pixels, 0, image.getWidth());

                ByteBuffer buffer = BufferUtils.createByteBuffer(image.getWidth() * image.getHeight()     *                              4); //4 for RGBA, 3 for RGB

            for(int y = 0; y < image.getHeight(); y++){
                for(int x = 0; x < image.getWidth(); x++){
                    int pixel = pixels[y * image.getWidth() + x];
                    buffer.put((byte) ((pixel >> 16) & 0xFF));     // Red component
                    buffer.put((byte) ((pixel >> 8) & 0xFF));      // Green component
                    buffer.put((byte) (pixel & 0xFF));               // Blue component
                    buffer.put((byte) ((pixel >> 24) & 0xFF));    // Alpha component. Only for RGBA
                }
            }

            buffer.flip();
            GL11.glEnable(GL11.GL_TEXTURE_2D);
            int textureID = GL11.glGenTextures();
           GL11.glTexImage2D(GL11.GL_TEXTURE_2D, 0, GL11.GL_RGBA8, image.getWidth(), image.getHeight(), 0, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buffer);
        return new TextureObject(textureID, image.getWidth(), image.getHeight());   
    }

Searching through similar problems all returned the same cause, not enabled GL_TEXTURE_2D.
I've enabled this, as well as given my quad texture coords.
When I bind my texture and attempt to render it, opengl decides it want's to make the whole screen white. I have Slick-Util in my project for testing, and it renders things fine.
However, if I have the following code in my render() function:

    GL11.glColor3f(1.0F, 1.0F, 1.0F);    

    if(RenderUtil.fontTexture != null) RenderUtil.renderTexturedQuad(RenderUtil.fontTexture, 40,     40, 150, 150);
    Main.t.bind();
    GL11.glBegin(GL11.GL_QUADS);
    GL11.glTexCoord2f(0, 0);
    GL11.glVertex2f(0, 0);
    GL11.glTexCoord2f(0, 1);
    GL11.glVertex2f(0, 512);
    GL11.glTexCoord2f(1, 1);
    GL11.glVertex2f(512, 512);
    GL11.glTexCoord2f(1, 0);
    GL11.glVertex2f(512, 0);
    GL11.glEnd();

... mainly the if(RenderUtil.fontTexture != null) RenderUtil.renderTexturedQuad(RenderUtil.fontTexture, 40, 40, 150, 150), OpenGL will not render anything. Even binding a slick texture and attemping to render that will fail. Here is the renderTexturedQuad() method in full:

public static void renderTexturedQuad(TextureObject texture, int x, int y, int w, int h)
{
    GL11.glColor3f(1.0F, 1.0F, 1.0F);
    GL11.glEnable(GL11.GL_TEXTURE_2D);
    TextureUtil.bind(texture);
    GL11.glPushMatrix();
    GL11.glTranslatef(x, y, 0);
    GL11.glBegin(GL11.GL_QUADS);
    GL11.glTexCoord2f(0, 0);
    GL11.glVertex2f(0, 0);
    GL11.glTexCoord2f(0, 1);
    GL11.glVertex2f(0, h);
    GL11.glTexCoord2f(1, 1);
    GL11.glVertex2f(w, h);
    GL11.glTexCoord2f(1, 0);
    GL11.glVertex2f(w, 0);
    GL11.glEnd();
    GL11.glPopMatrix();
}

The only thing I see that could be setting things wrong is the binding of my texture?

I'd prefer if you didn't refer me to a library or equivalent, this is a learning experience :)

Upvotes: 0

Views: 390

Answers (1)

Zaide Chris
Zaide Chris

Reputation: 361

You need to bind the texture before you load the image data in to it. If you don't glTexImage2D doesn't know where to load the data.

You can bind the texture by calling:

GL11.glBindTexture(GL11.GL_TEXTURE_2D, textureID);

Before:

GL11.glTexImage2D(GL11.GL_TEXTURE_2D, 0, GL11.GL_RGBA8, image.getWidth(), image.getHeight(), 0, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buffer);

You should also call these lines after you load the image data:

    GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_S, GL11.GL_REPEAT);
    GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_T, GL11.GL_REPEAT);
    GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);
    GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_NEAREST);

Upvotes: 1

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