/////////////////////////////////////////////////////////////////////////////
// showst.osl - simple shader to color based on s,t
//
// Description:
//   This is a debugging shader to help you examine the s,t texture
//   coordinates by stuffing them in the red and green channels.
// 
// Parameters:
//   s,t - texture coordinates (default to u,v)
//
/////////////////////////////////////////////////////////////////////////////
// Copyright 2004 NVIDIA Corporation.  All Rights Reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// 
// * Redistributions of source code must retain the above copyright
//   notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the distribution.
// * Neither the name of NVIDIA nor the names of its contributors
//   may be used to endorse or promote products derived from this software
//   without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// (This is the Modified BSD License)
/////////////////////////////////////////////////////////////////////////////


surface
showst 
    [[ string description = "Color s in red, t in green (for debugging)" ]]
(
    float use_lighting = 0
        [[  string description = "Surface responds to lighting",
            string UItype = "bool" ]],
    float desaturate_backface = 0
        [[  string description = "De-saturate backfacing geometry",
            string UItype = "bool" ]],
    float Ka = 1
        [[  string description = "Ambient scaling",
            float UImin = 0, float UIsoftmax = 1 ]],
    float Kd = .5
        [[  string description = "Diffuse scaling",
            float UImin = 0, float UIsoftmax = 1 ]],
    float Ks = .5
        [[  string description = "Specular scaling",
            float UImin = 0, float UIsoftmax = 1 ]],
    float roughness = .1
        [[  string description = "Surface roughness (specular highlight size)",
            float UImin = 0, float UImax = 1,
            string UIenabler = "Ks" ]],
    color specularcolor = 1
        [[  string description = "Specular highlight color",
            string UIenabler = "Ks" ]],
    float s = u
        [[  string description = "s texture coordinate (defaults to u)",
            string UIenabler = "texturename" ]],
    float t = v
        [[  string description = "t texture coordinate (defaults to v)",
            string UIenabler = "texturename" ]]
  )
{
    /* basic color is based on s,t coordinates */
    C = color (s, t, 0.1);
    /* desaturate backfacing */
    if (desaturate_backface  &&  dot(Ng, I) > 0)
        C = 0.3 * C + color(.3, .3, .3);

    if (use_lighting) {
        normal Nf = faceforward (normalize(N),I);
        C = C * (Ka*ambient() + Kd*diffuse(Nf)) +
            specularcolor * Ks*specular(Nf,-normalize(I),roughness);
    }

    C *= opacity;
}
