Transparent depth for Cycles Volumetrics

Hello!

I’ve been a little disappointed that cycles can’t currently create realistic clouds like rendering engines such as Arnold can (see link: docs.arnoldrenderer.com/display/A5AFMUG/Rendering+a+Cloud ).

Cycles’ volume rendering engine is already pretty decent, but it simply doesn’t have the same capabilities as a rendering engine like Arnold in the volumetric department.

I propose that a transparent depth parameter be added to the volume scattering and principled volume nodes.

It would be INCREDIBLY simple, here’s all that needs to be done:

in Blender 3.0\3.0\scripts\addons\cycles\source\kernel\closure\volume.h:

in the volume extinction function:

 /* VOLUME EXTINCTION */

 ccl_device void volume_extinction_setup(ccl_private ShaderData *sd, float3 weight)
 {
      if (sd->flag & SD_EXTINCTION) 
      {
           sd->closure_transparent_extinction += 
      weight;
      } else {
           sd->flag |= SD_EXTINCTION;
           sd->closure_transparent_extinction = weight;
      }
 }

replace it with this function:

 /* VOLUME EXTINCTION */

 ccl_device void volume_extinction_setup(ccl_private ShaderData *sd, float3 weight, float transparentDepth)
 {
      if (sd->flag & SD_EXTINCTION) 
      {
           sd->closure_transparent_extinction += 
      weight/transparentDepth;
      } else {
           sd->flag |= SD_EXTINCTION;
           sd->closure_transparent_extinction = weight/transparentDepth;
      }
 }

and obviously, update the references, and also add a transparent depth parameter to the cycles volume scatter node and the principled volume node, which theoretically should be no more than a few minutes of work that would help me and probably hundreds of other artists create more realistic volumetric materials.