Control alpha of triangles

u7angel · July 28, 2010, 5:58pm

hlsl shader question

is it possible to control alpha of triangles depending on their orientation ?

what i’m trying to do is getting rid of vertical triangles and leave horizontal triangles. see image, the bright vertical are meant to be invisible.

i don’t want anybody to do it…but just generally is it possible ?

thanx

tonfilm · July 28, 2010, 6:28pm

you could try this code snippet:

float3 alphaDir;
float3 faceNormal;

alpha = dot(normalize(alphaDir), normalize(faceNormal))) < angleEpsillon;

where angleEpsilon is close to 1.

u7angel · July 28, 2010, 8:29pm

thanks for the skype support!

here is the result, for whom it might concern. i’ll get on implementing this into another shader.