Color Ramp in PBR Lighting Material

carpenter · December 21, 2021, 11:43am

I recently knew that GLTF format uses PBR workthrough so if I want to use toon shading, I just can’t directly use it cause PBRLighting doesn’t have ColorRamp property
so the only solution I have now is converting PBRLighting to phong Lighting
so I want to ask is there any other solution?

pspeed · December 21, 2021, 2:13pm

I mean, if you aren’t going to use any of the PBR features then converting to standard lighting (if that’s what’s been working for you) seems like the best choice.

Should be only a few lines of code in a scene graph visitor to convert your model from one material to another and transfer the right textures, etc…

Edit: or if you used JMEC or the SDK to convert your model, you could output the j3m files and just edit them.

Ali_RS · December 21, 2021, 2:45pm

Hi

Nothing to add to the topic.

I’m interested to know more about this property in Phong lighting. Can someone please explain what is this for?

Thanks

pspeed · December 21, 2021, 2:56pm

From the code:

github.com

jMonkeyEngine/jmonkeyengine/blob/master/jme3-core/src/main/resources/Common/MatDefs/Light/Lighting.frag#L209

    
      
             if(spotFallOff <= 0.0){

                 gl_FragColor.rgb = AmbientSum * diffuseColor.rgb;

                 gl_FragColor.a   = alpha;

                 return;

             }

            }        

          #endif

          

          vec2   light = computeLighting(normal, viewDir, lightDir.xyz, lightDir.w * spotFallOff, m_Shininess) ;

          #ifdef COLORRAMP

               diffuseColor.rgb  *= texture2D(m_ColorRamp, vec2(light.x, 0.0)).rgb;

               specularColor.rgb *= texture2D(m_ColorRamp, vec2(light.y, 0.0)).rgb;

               light.xy = vec2(1.0);

          #endif

          

          // Workaround, since it is not possible to modify varying variables

          vec4 SpecularSum2 = vec4(SpecularSum, 1.0);

          #ifdef USE_REFLECTION

               vec4 refColor = Optics_GetEnvColor(m_EnvMap, refVec.xyz);

          

               // Interpolate light specularity toward reflection color

It uses the amount of direct lighting (based on normal, lighting vector, etc.) to lookup a color multiplier.

To me this indicates that you could provide harsh shadows or harsh highlights, etc… depending on how your ramp is setup. Maybe others have more practical examples.

carpenter · December 22, 2021, 7:43am

thank you
then I’ll stick with materials converting process

carpenter · December 22, 2021, 7:55am

It’s a property to simulate Cel shading, cell shading or toon shading

Ali_RS · December 23, 2021, 7:19am

Thanks

@carpenter I would be interested to see a screenshot of your scene using this effect if you do not mind

carpenter · December 23, 2021, 2:06pm

This is just a simple scene to experiment on gltf model
toon

Ali_RS · December 23, 2021, 2:37pm

Nice!

Are you using a grayscale ramp texture for this?

carpenter · December 26, 2021, 8:20am

yes …
the default one in the sdk

Ali_RS · December 26, 2021, 9:05am

Will appreciate if you can upload it here or give me a link to it, please. Unfortunately, I do not have the SDK installed.

Thanks

carpenter · December 26, 2021, 9:44am

here it is
the image
https://hub.jmonkeyengine.org/uploads/default/original/4X/1/0/f/10f4a4b8f7a1aa43609e5cae0002aa66021a379e.png

Ali_RS · December 26, 2021, 1:56pm

Thanks!

carpenter · December 27, 2021, 7:54am

you’re welcome
thank you for your great works