testshade --shader <shadername> <layername>

[lgritz]

--shader is like a combination of --layer, and then naming the shader to create an instance of it.

The reason I prefer --shader is that when you use it, the command line is almost identical to the shader group serialization. So much nicer!

For example:

$ testshade -param texturename "grid.tx" \
            -shader texturemap tex1 \
            -param frequency 4.0 \
            -shader noisy noise1 \
            -param scale 1.0 \
            -shader contrast cont1 \
            -shader umixer mix1 \
            -connect tex1 out cont1 in \
            -connect cont1 out mix1 left \
            -connect noise1 out mix1 right \
            -g 256 256 -o out noisetex.jpg

corresponds very symmetrically to the shader group

param texturename "grid.tx" ;
shader texturemap tex1 ;
param frequency 4.0 ;
shader noisy noise1 ;
param scale 1.0 ;
shader contrast cont1 ;
shader umixer mix1 ;
connect tex1.out cont1.in ;
connect cont1.out mix1.left ;
connect noise1.out mix1.right ;

whereas, in comparison, using the old --layer notation works, but is
a less direct mapping to the serialization format:

$ testshade -layer tex1 -param texturename "grid.tx" texturemap \
            -layer noise1 -param frequency 4.0 noisy \
            -layer cont1 -param scale 1.0 contrast \
            -layer mix1 umixer \
            -connect tex1 out cont1 in \
            -connect cont1 out mix1 left \
            -connect noise1 out mix1 right \
            -g 256 256 -o out noisetex.jpg

[fpsunflower]

LGTM