Alpha doesnt work

Newbie & Debugging Questions
#1

Using JOGL, and problem is - there is no alpha. I have a PNG file that shows transparency in photoshop.

Loading texture:

	public void LoadTextureFromResource(String res,String type) throws IOException
	{
		
        InputStream stream = getClass().getResourceAsStream(res);
        TextureData data = TextureIO.newTextureData(GLProfile.getDefault(),stream,GL2.GL_RGBA,GL2.GL_RGBA, false, type);
        this.texture = TextureIO.newTexture(data);
        this.loaded = true;
	}

OpenGL init:

        GLCapabilities capabilities = new GLCapabilities(GLProfile.getDefault());
        capabilities.setHardwareAccelerated(true);
        capabilities.setNumSamples(0);
        capabilities.setAlphaBits(8);
        capabilities.setSampleBuffers(true);

        ......
       
        gl.glDisable(GL2.GL_LIGHTING);
	gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);  // <--
	gl.glEnable (GL2.GL_BLEND); 
        gl.glShadeModel(GLLightingFunc.GL_SMOOTH);
        gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        gl.glClearDepth(1.0f);
        gl.glEnable(GL.GL_DEPTH_TEST);
        gl.glDepthFunc(GL.GL_LEQUAL);
        gl.glHint(GL2ES1.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST);

Tried changing blend func, some modes make everything transparent, this one renders fine but without alpha.
And ofcourse, im rendering object with that texture last.

Help??

#2

Don’t know if this will help but here is what I needed to do to get alpha textures in lwjgl.


    glEnable(GL_BLEND)
    glDisable(GL_DITHER)
    glDisable(GL_FOG)
    glDisable(GL_LIGHTING)
    glEnable(GL_LINE_SMOOTH)
    glDisable(GL_TEXTURE_1D)
    glEnable(GL_TEXTURE_2D)

    //glShadeModel(GL_FLAT)
    glShadeModel(GL_SMOOTH)

    //glPolygonMode(GL_FRONT, GL_LINE)
    glPolygonMode(GL_FRONT, GL_FILL)

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)

    glEnableClientState(GL_VERTEX_ARRAY)
    glEnableClientState(GL_TEXTURE_COORD_ARRAY)
    glEnableClientState(GL_COLOR_ARRAY)
#3

Almost everything i have ??? :-\

#4

You have depth testing enabled, which will defeat blending. You need to disable it.

#5

still doesn’t work, and i see poligons thru walls.

#6

ok made a progress, removed default color from objects, only texture now.

now on areas where should be transparent, i have red color? :smiley:

EDIT: its not the background, background is blue

#7

ok, found a problem: gl.glTexEnvi (GL2.GL_TEXTURE_ENV, GL2.GL_TEXTURE_ENV_MODE, GL2.GL_DECAL);

after removing* that transparency works, but everything is red… its red becouse of font rendering.

is there a way to reset opengl color after calling glColor?? and another way to use only texture color no lights?

#8

Seems like R and A are in the wrong place (GL2.GL_RGBA).

Is there an GL_ARGB version?

#9

setting glColor to white, fixes the problem… but the scene is a little brighter.

The following code was causing alpha to fail:

gl.glTexEnvi (GL2.GL_TEXTURE_ENV, GL2.GL_TEXTURE_ENV_MODE, GL2.GL_DECAL);