Texture "disappears"

[mightymarcus]

I am very new to OpenGL and to get into it I started coding a little GUI on top of BJS. 

Before the scene.render() I draw some textured triangles (a spritesheet with a font) to a framebuffer object that is connected to a BJS-Texture which I use on a regular BJS Plane Mesh.

It all works as desired, when I draw to the texture before the first scene.render() call. But when I want to update the text (drawing again to the texture) on the next scene.render() call it gives me:

There is no texture bound to the unit 0.

The strange thing is, when I create a new Texture that is not connected to anything, just creating it, it works. And it has to be a texture that was not loaded before (is not in the cache).

    

	public static function update()
	{
		for (props in _textsToDraw)
		{
			var texture = new Texture("textures/" + _textures[_texturenum], Gfx.scene);
			var instance:TextRenderer = props.instance;
			instance._drawText(cast props.text, cast props.posX, cast props.posY);
			_texturenum++;		
		}
		
		_textsToDraw.splice(0, _textsToDraw.length);
	}

So I think on the scene.render() function it happens something like that the texture with the font is overriden or is changing somehow. I really can't tell.

Because I am just starting with OpenGL/WebGL I have not really the idea of changing states and what exactly happens "inside" BJS.

Maybe someone can give me a pointer how I could solve this problem with the "disappearing" texture.

Once again what happens:

1. Drawing to the framebuffer that is connected to the BJs Texture.

2. first scene.render(); call

OK. The texture is updated with the text.

3. Drawing to the framebuffer again

4. scene.render()

There is no texture bound to the unit 0 (it has to be the font texture, becaus when I just draw the background which has no texture it works)

But doing

1. Drawing to the framebuffer that is connected to the BJs Texture.

2. first scene.render(); call

OK. The texture is updated with the text.

3. creating a temporary BJS Texture before drawing to the framebuffer

4. scene.render()

5. It is working ...

This is the relevant code that renders the buffers..

	function _render()
	{
		GL.enable(GL.BLEND);
		GL.blendFunc(GL.SRC_ALPHA, GL.ONE_MINUS_SRC_ALPHA);		
		GL.viewport(0, 0, 512, 512);		
		GL.clearColor(0.0, 0.0, 0.0, 1.0);
		GL.colorMask(true, true, true, true);
		GL.disable(GL.DEPTH_TEST);
		GL.disable(GL.CULL_FACE);		
		GL.clear(GL.COLOR_BUFFER_BIT);
		//GL.blendEquation(GL.FUNC_ADD);
		
		GL.bindFramebuffer(GL.FRAMEBUFFER, _textureFramebuffer);		
		
		_drawBackground();
		_drawContent();
		
		GL.bindFramebuffer(GL.FRAMEBUFFER, null);		
		GL.useProgram(null);
		GL.enable(GL.DEPTH_TEST);
		GL.enable(GL.CULL_FACE);
	}	
	
	function _drawContent()
	{
		GL.useProgram(_textContentProgram);
		
		var matrix = Matrix4.createOrtho(0, 512, 512, 0, -1000, 1000);
		GL.uniformMatrix4fv(_textContentMatrixUniform, false, matrix);
		
		GL.uniform4fv(_textContentTextColorUniform, new Float32Array([_textColor.r, _textColor.g, _textColor.b, _textColor.a]));
		
		GL.activeTexture(GL.TEXTURE0);
		
		GL.bindTexture (GL.TEXTURE_2D, _fontTexture);
		
		GL.bindBuffer(GL.ARRAY_BUFFER, _contentVertexBuffer);
								
		GL.enableVertexAttribArray(_textContentVertexAttr);
		GL.enableVertexAttribArray(_textContentTextureAttr);
		GL.vertexAttribPointer (_textContentVertexAttr, 3, GL.FLOAT, false, 5 * Float32Array.BYTES_PER_ELEMENT, 0);
		GL.vertexAttribPointer (_textContentTextureAttr, 2, GL.FLOAT, false, 5 * Float32Array.BYTES_PER_ELEMENT, 3 * Float32Array.BYTES_PER_ELEMENT);
		
		GL.drawArrays(GL.TRIANGLES, 0, _numVertices);
		
		GL.disableVertexAttribArray(_textContentVertexAttr);
		GL.disableVertexAttribArray(_textContentTextureAttr);
		
		//GL.activeTexture(GL.TEXTURE0 );
		GL.bindTexture(GL.TEXTURE_2D, null);
	}

 

[mightymarcus]

Look at this. FakeTexture is almost empty, I deleted almost the entire code an there is no image loaded. But with that it works. That's the ugliest "workaround" of all time I think..

	public static function update()
	{
		for (props in _textsToDraw)
		{
			// :(
			var texture = new FakeTexture("ugly", Engine3D.fakeScene);
			texture.dispose();
			
			var instance:TextRenderer = props.instance;
			instance._drawText(cast props.text, cast props.posX, cast props.posY);
		}
		
		_textsToDraw.splice(0, _textsToDraw.length);
	}

 

[mightymarcus]

Oh man oh man. I'm such a noob. And is was so easy ... 

After drawing the text I had to GL.bindTexture the texture that was bound before I bount the sprite sheet. I thought BJS would do this in every render call itself. That was all ... Now I only have to find out what textureID was bound before the text drawing ...

[GameMonetize]

I would say: Good job