Sunday, April 17, 2011

Writing mental ray shaders: UV Chooser

Here is a shader that loads a texture, and chooses which UV set to use. There's an equivalent node in Maya, but it requires setting the input values in hypershade, which isn't intuitive for the avg user. In 3ds max the same thing is set with UV channels. Multi texture layering is an important technique when dealing repetitive textures, by using 5 1k textures, i can create a better looking texture than a single 5k texture. Not sure why maya is making it so hard for avg users.

MI Source
declare shader
 color "uv_chooser" (
  color texture "tex",
  integer "uv_sets"
apply material
end declare

C Source
#include "shader.h"

struct uv_chooser{
 miTag tex;
 miInteger uv_sets;

miBoolean uv_chooser(miColor *result, miState *state, struct uv_chooser *params) {
 miTag tex = *mi_eval_tag(&params->tex);
 miInteger uv_sets = *mi_eval_integer(&params->uv_sets);
 int i = uv_sets;
 mi_lookup_color_texture(result, state, tex, &state->tex_list[i]);
 return miTRUE;



Post a Comment