// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Doug L. James and Ethan James

///////////////////////////////////////////////////////////////////////
////  Simple UV Test Shader for Redshift OSL                         //
////  Use this to verify OSL is working before testing Mixwell       //
///////////////////////////////////////////////////////////////////////

shader Mixwell_UV_Test(
    float uvScale = 1.0
        [[ string label = "UV Scale" ]],
    float gridLines = 10.0
        [[ string label = "Grid Lines" ]],
    
    output color outColor = 0
)
{
    float uu = u * uvScale;
    float vv = v * uvScale;
    
    // Grid pattern
    float gx = step(0.95, mod(uu * gridLines, 1.0));
    float gy = step(0.95, mod(vv * gridLines, 1.0));
    float grid = max(gx, gy);
    
    // UV gradient with grid overlay
    outColor = color(mod(uu, 1.0), mod(vv, 1.0), 0.0) + color(grid, grid, grid);
}