Texture not working

Newbie & Debugging Questions
#1

Hi,

Trying to apply a texture to a cube, texture is 512x512 in size, although image is 300x300.

This is the code to render cube in immediate mode:


	GL11.glTexEnvf( GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL11.GL_MODULATE );
		
	//	GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER,
      //          			  GL11.GL_LINEAR_MIPMAP_NEAREST );

		//when texture area is large, bilinear filter the original
		GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_LINEAR );

		//the texture wraps over at the edges (repeat)
		GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_S, GL11.GL_REPEAT );
		GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_T, GL11.GL_REPEAT );

		GL11.glBindTexture(GL11.GL_TEXTURE_2D, texture.getTextureID());

		GL11.glPushMatrix();
		GL11.glTranslatef(0, 2, 8);
		GL11.glRotatef(20, 1, 0, 1);
		GL11.glBegin(GL11.GL_QUADS);
		GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Left
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Right
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f( 1.0f,  1.0f,  1.0f);	// Top Right
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f(-1.0f,  1.0f,  1.0f);	// Top Left
        // Back Face
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Right
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Right
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Left
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Left
        // Top Face
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Left
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f(-1.0f,  1.0f,  1.0f);	// Bottom Left
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f( 1.0f,  1.0f,  1.0f);	// Bottom Right
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Right
        // Bottom Face
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Top Right
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Top Left
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Left
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Right
        // Right face
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Right
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Right
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f( 1.0f,  1.0f,  1.0f);	// Top Left
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Left
        // Left Face
        GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Left
        GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Right
        GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f(-1.0f,  1.0f,  1.0f);	// Top Right
        GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Left
        GL11.glEnd();
        GL11.glPopMatrix();
	}

I load the texture as (using slick util):


try {
			
	texture = TextureLoader.getTexture("PNG",ResourceLoader.getResourceAsStream("res/grass.png"));
		
		} catch (IOException e) {
			System.out.println(e.getMessage());
		}

I enable texture2d at start.

Screenshot here:


https://sites.google.com/site/debugopengl/

Maybe I need to generate the mipmaps? It is strange as the whole screen as gone green?!
If I uncomment this line:


GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER,
                			  GL11.GL_LINEAR_MIPMAP_NEAREST );

then no texture is applied?

Any help with this is appreciated.

#2

You need to bind the texture before calling all the texture functions at the top.

#3

Thanks for looking, but still exactly the same effect…

#4

SlickUtil is outdated and buggy; it sometimes does weird things with GL states. It also doesn’t support non-power-of-two textures – it will pad them with empty pixels, which means you need to adjust your glTexCoord2f parameters accordingly.

It also seems like you don’t really know what you’re doing, and just copy + pasting code together from different (outdated) tutorials… I’d really suggest starting off with 2D, maybe following some more modern tutorials and ensuring you have a strong grasp of all the concepts before moving onto the next steps:
LWJGL Display
LWGL Textures

#5

@davedes thanks for your comments and links.

Just knew to OpenGL, not to programming :wink:

Will look at the links you sent - do you suggest not using slick?

#6

Here’s my code for making a texture from an image.
I recommend wrapping it in an object and giving it a bind function for ease of use.

http://pastebin.java-gaming.org/8ddc7531e52

#7

Thanks for that :slight_smile:

I got the texture on the cube working, made the image a power of 2. Although, the whole
screen is still green - the colour of the texture?!

#8

Getting very strange results. I’ve got a debug wireframe cube I draw, if I draw this, my textured cube is then a different colour - it is the colour of the debug wireframe cube…

I think as OpenGL is a state machine, I’m messing up somewhere with states? Is there some rules for this?

The textured cube seems to use the last objects states?

What is even more strange is I don’t even need to bind the texture for it to appear on the cube???

Thanks,

#9

Update:

I’ve been modifying the code somewhat, and now I get the texture on ok, but my other objects appear in incorrect colour - basically the colour the texture is?!

So, if my texture is say a crate (so mostly brown colours), then the rest of my objects will also take on this colour, even though I’m setting them a different colour? If my texture is grass (so prodomenitarly green), all my other objects will take on this colour. I’m clueless as to what is happening here.

Anybody any ideas? My setup is this:


	private void InitGL() {
				 
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();

		gluPerspective(
				  45.0f,
				  (float) Display.getWidth() / (float) Display.getHeight(),
				  0.1f,
				  100.0f);

		
		GL11.glTranslatef(0, -2f, 0f);
		GL11.glRotatef(180.0f, 0, 1.0f, 0);

		glMatrixMode(GL_MODELVIEW);
		GL11.glLoadIdentity();
		GL11.glEnable(GL11.GL_TEXTURE_2D);
		glShadeModel(GL_SMOOTH);
		glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
		glClearDepth(1.0);
		glEnable(GL_DEPTH_TEST);
		GL11.glEnable(GL11.GL_BLEND);
		GL11.glDepthFunc(GL11.GL_LEQUAL);
		GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST);

		this.loadTextures();

	}

and my textured cube rendered:


private void renderACube()
	{
		glLoadIdentity();

		org.newdawn.slick.Color.white.bind();
		
		GL11.glTranslatef(0, 0, 8);
		
		GL11.glRotatef(20,1.0f,0.0f,0.0f);	 // Rotate On The X Axis
		GL11.glRotatef(10,0.0f,1.0f,0.0f);	 // Rotate On The Y Axis
		GL11.glRotatef(65,0.0f,0.0f,1.0f);	 // Rotate On The Z Axis
		
		texture.bind();
		GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_NEAREST );
		GL11.glTexParameterf( GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_NEAREST );
	
		GL11.glBegin(GL11.GL_QUADS);

		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f(-1.0f, -1.0f, 1.0f);	// Bottom Left Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f( 1.0f, -1.0f, 1.0f);	// Bottom Right Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f( 1.0f, 1.0f, 1.0f);	// Top Right Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f(-1.0f, 1.0f, 1.0f);	// Top Left Of The Texture and Quad
		// Back Face
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Right Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f(-1.0f, 1.0f, -1.0f);	// Top Right Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f( 1.0f, 1.0f, -1.0f);	// Top Left Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Left Of The Texture and Quad
		// Top Face
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f(-1.0f, 1.0f, -1.0f);	// Top Left Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f(-1.0f, 1.0f, 1.0f);	// Bottom Left Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f( 1.0f, 1.0f, 1.0f);	// Bottom Right Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f( 1.0f, 1.0f, -1.0f);	// Top Right Of The Texture and Quad
		// Bottom Face
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Top Right Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Top Left Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f( 1.0f, -1.0f, 1.0f);	// Bottom Left Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f(-1.0f, -1.0f, 1.0f);	// Bottom Right Of The Texture and Quad
		// Right face
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Right Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f( 1.0f, 1.0f, -1.0f);	// Top Right Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f( 1.0f, 1.0f, 1.0f);	// Top Left Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f( 1.0f, -1.0f, 1.0f);	// Bottom Left Of The Texture and Quad
		// Left Face
		GL11.glTexCoord2f(0.0f, 0.0f);
		GL11.glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Left Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 0.0f);
		GL11.glVertex3f(-1.0f, -1.0f, 1.0f);	// Bottom Right Of The Texture and Quad
		GL11.glTexCoord2f(1.0f, 1.0f);
		GL11.glVertex3f(-1.0f, 1.0f, 1.0f);	// Top Right Of The Texture and Quad
		GL11.glTexCoord2f(0.0f, 1.0f);
		GL11.glVertex3f(-1.0f, 1.0f, -1.0f);	// Top Left Of The Texture and Quad		
        GL11.glEnd();
	}

	public void loadTextures() 
	{
		try {
			// load texture from PNG file
			texture = TextureLoader.getTexture("PNG", ResourceLoader.getResourceAsStream("res/grass.png"));
		
		} catch (IOException e) {
			System.out.println(e.getMessage());
		}
	}

All the other objects which are just blocks with no texture are stored in an arraylist which are then all rendered, basically block looks like:


private void renderBlock(Block.BlockType type) {
		     
			 if(type == BlockType.BlockType_Grass)
				 glColor3f(0.0f, 1.0f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(94/255f, 58/255f,41/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(1.0f, 1.0f, 1.0f);
				 
	         off_glVertex3f(0.5f, 0.5f, -0.5f);
	         off_glVertex3f(-0.5f, 0.5f, -0.5f);
	         off_glVertex3f(-0.5f, 0.5f, 0.5f);
	         off_glVertex3f(0.5f, 0.5f, 0.5f);
	         
			 if(type == BlockType.BlockType_Grass)
		         glColor3f(0.0f, 0.4f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(92/255f, 61/255f,45/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(0.84f, 0.84f, 0.84f);
	         off_glVertex3f(0.5f, -0.5f, 0.5f);
	         off_glVertex3f(-0.5f, -0.5f, 0.5f);
	         off_glVertex3f(-0.5f, -0.5f, -0.5f);
	         off_glVertex3f(0.5f, -0.5f, -0.5f);
	         
			 if(type == BlockType.BlockType_Grass)
		         glColor3f(0.0f, 0.8f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(94/255f, 70/255f,58/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(0.8f, 0.8f, 0.8f);
	         off_glVertex3f(0.5f, 0.5f, 0.5f);
	         off_glVertex3f(-0.5f, 0.5f, 0.5f);
	         off_glVertex3f(-0.5f, -0.5f, 0.5f);
	         off_glVertex3f(0.5f, -0.5f, 0.5f);
	         
			 if(type == BlockType.BlockType_Grass)
		         glColor3f(0.0f, 0.7f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(110/255f, 81/255f,67/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(.9f, 0.9f, 0.9f);
	         off_glVertex3f(0.5f, -0.5f, -0.5f);
	         off_glVertex3f(-0.5f, -0.5f, -0.5f);
	         off_glVertex3f(-0.5f, 0.5f, -0.5f);
	         off_glVertex3f(0.5f, 0.5f, -0.5f);
	         
			 if(type == BlockType.BlockType_Grass)
		         glColor3f(0.0f, 0.6f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(110/255f, 78/255f,63/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(0.75f, 0.75f, 0.75f);
	         off_glVertex3f(-0.5f, 0.5f, 0.5f);
	         off_glVertex3f(-0.5f, 0.5f, -0.5f);
	         off_glVertex3f(-0.5f, -0.5f, -0.5f);
	         off_glVertex3f(-0.5f, -0.5f, 0.5f);
	         
			 if(type == BlockType.BlockType_Grass)
		         glColor3f(0.0f, 0.5f, 0.0f);
			 if(type == BlockType.BlockType_Dirt)
				 glColor3f(110/255f, 73/255f,55/255f);
			 if(type == BlockType.BlockType_Snow)
				 glColor3f(0.7f, 0.7f, 0.7f);
	         off_glVertex3f(0.5f, 0.5f, -0.5f);
	         off_glVertex3f(0.5f, 0.5f, 0.5f);
	         off_glVertex3f(0.5f, -0.5f, 0.5f);
	         off_glVertex3f(0.5f, -0.5f, -0.5f);
	   }

// avoids us having to do a slow glTranslatef
private void off_glVertex3f(float x,float y,float z){
	         glVertex3f(tx+x,ty+y,tz+z);
}

and my update loop: (taken out other bits of code for keyboard detection, camera movement…)


try {
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		ChunkManager.getInstance().render();  // render all blocks in world
		this.renderACube(); // render the textured cube				
		Display.update();
		Display.sync(60);
	} catch (Exception e) {
	}

Anything obvious stand out?!

Many thanks

#10

I always cringe when I see catch blocks that do nothing. There might not be any exceptions raised within the block, but how would you know? At the very least you should be writing something to System.out but even that isn’t always sufficient. In your loadTextures code you catch an IOException, write the error message but carry on as if nothing happened. How do you know if the texture is loaded?

In my opinion this sort of thing is just asking for trouble - or worse - ignoring the trouble when it happens.

#11

Sorry, I didn’t show the code in the catch block for clarification purposes.

Of course I always put exception code in there, but this isn’t the issue.

I’ve uploaded a new screen shot at:


https://sites.google.com/site/debugopengl/

What I am struggling with to understand is that I don’t need to bind the texture for it
to appear on the cube?

Regards

** UPDATE - this is now working, forgot to disable texturing for blocks that don’t use a texture…