GLSL Shader support that renders tiles correctly

[tve]

Hi All,

I haven't been working with WWJ for a while now, but I have had several requests for help with getting the tile renderer working correctly with GLSL shaders as in the application screenshots I have submitted. I submitted the code for inclusion with WWJ some time ago, but never received a response. I will just post some sample code here in case it might help someone out. Have fun.
tve

http://picasaweb.google.com/tve9999/...indJavaImages#

[patmurris]

Thanks for the little Christmas present
I have been experimenting a bit with shaders too, but it is not a priority to integrate them in the SDK yet. It will come at some point so be assured i'm keeping your contributions in a safe place for that.

[baellwe]

good work, your screens are awesome.

[Omega]

Thanks very much tve!

I've been trying to get shaders working for a while, but the tiling was messed up. The solution was found in your fragment shader: I wasn't discarding when the alpha texture was less than 1.

It is possible to use shaders without modifications to the SurfaceTileRenderer class. Simply create a layer that you wish to be shaded, and override the render(DrawContext dc) function like so:

	public void render(DrawContext dc)
	{
		GL gl = dc.getGL();
		gl.glUseProgram(shaderprogram);
		super.render(dc);
		gl.glUseProgram(0);
	}

Note: you must initialize the shaderprogram sometime in the GL thread.

[Gor]

hi tve, i have no experience with shaders. Can you provide and example or more information about how to produce this output:
http://picasaweb.google.com/tve9999/...36747054820562

thx
gor

[tve]

Omega,
No problem. I'm glad you found the example useful. Hopefully we will see shaders integrated into the core one of these days.

Gor,
I will try to put something together for implementing that demo. I submitted code at one time to implement that very screen shot. It was not integrated at that time because shaders are a low priority for the WWJ team. The WWJ base code has changed significantly since then and it will probably take me some time to figure out how to get it working again.

-tve
http://geoagsys.com/
http://tve-consulting.com/

Originally Posted by Omega

Thanks very much tve!

[what_nick]

I am working on shaders for WMS based layers ... based on the simple override of render method and fragment shaders. I am going to reuse the GLSL class supplied to manage the set of shaders. I will come back with results as soon as I have something sensible.

Cheers,

what_nick

[what_nick]

That was ridiculously simple once I figured out how to pass the textures to the shader. This is what i have in my class extended from WMSTiledImageLayer:

//Override render allow application of shaders
    
    @Override
    public void render(DrawContext dc) {
        // TODO Auto-generated method stub
        glsl.useShaders();
        glsl.startShader();
        GL gl = dc.getGL();
        gl.glUniform1i(glsl.getUniformLocation("tile_image"),0);    //use texture unit 0
        gl.glUniform1i(glsl.getUniformLocation("alpha_mask"),1);    //use texture unit 1
        super.render(dc);
        glsl.endShader();
    }

    //Load shaders in the pre-render pass
    @Override
    protected void doPreRender(DrawContext dc) {
        // TODO Auto-generated method stub
        if(glsl==null)
        {
            glsl = new ContrastGLSL(dc.getGL());
            //System.out.println(glsl.isShaderSupported());
            glsl.loadVertexShader(ContrastGLSL.vertfile);
            glsl.loadFragmentShader(ContrastGLSL.fragfile);
        }
        super.doPreRender(dc);    
    }

And it works like a charm .. will fail on machines with no shader support but it is just a test.

Cheers,

what_nick.