gradientRoundedRect.cpp

const std::map<OpenGLData::OpenGLUniforms, String> OpenGLData::OpenGLUniformsMap =
{
    { OpenGLUniforms::Bounds,           "bounds"        },
    { OpenGLUniforms::InnerColor,       "innerColor"    },
    { OpenGLUniforms::OuterColor,       "outerColor"    },
    { OpenGLUniforms::Hollow,           "hollow"        },
    { OpenGLUniforms::RoundedBoxWidth,  "roundedBoxWidth"   },
    { OpenGLUniforms::RoundedBoxHeight, "roundedBoxHeight"  },
    { OpenGLUniforms::Gradient,         "gradient"      },
    { OpenGLUniforms::Radius,           "radius"        }
};

#define NEW_LINE "\n"

#define NEW_LINE "\n"
String makeFragmentShaderHeader()
{
    return
    "uniform vec4 " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::Bounds) + ";" NEW_LINE
    "uniform vec4 " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::InnerColor) + ";" NEW_LINE
    "uniform vec4 " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::OuterColor) + ";" NEW_LINE
    "uniform bool " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::Hollow) + ";" NEW_LINE
    "uniform float " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::RoundedBoxWidth) + ";" NEW_LINE
    "uniform float " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::RoundedBoxHeight) + ";" NEW_LINE
    "uniform float " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::Gradient) + ";" NEW_LINE
    "uniform float " + OpenGLData::OpenGLUniformsMap.at(OpenGLData::OpenGLUniforms::Radius) + ";" NEW_LINE
    ;
}
    String fragmentShader = makeFragmentShaderHeader() +

    "float roundedBox(vec2 point, vec2 rectBounds, float radius)"           NEW_LINE
    "{"                                                                     NEW_LINE
        //this returns the distance
    "    return length(max (abs(point) - rectBounds + radius, 0.0)) - radius;" NEW_LINE
    "}"                                                                     NEW_LINE

    "float hsluv_fromLinear(float c) {"                                     NEW_LINE
    "    return c <= 0.0031308 ? 12.92 * c : 1.055 * pow(c, 1.0 / 2.4) - 0.055;" NEW_LINE
    "}"                                                                     NEW_LINE

    "void main(void)"                                                       NEW_LINE
    "{"                                                                     NEW_LINE
        // Normalized pixel coordinates (from 0 to 1)
    "   vec2 normalizedFragCoord = gl_FragCoord.xy / bounds.xy;"            NEW_LINE
//    "    float ratio = bounds.y / bounds.x;"                                NEW_LINE
    //change normalized pixel coord range from [0,1] to [-1,1]
    "   vec2 p = normalizedFragCoord * 2.0 - 1.0;"                          NEW_LINE
    //remove y-axis scaling from normalizing
//    "    p.y *= ratio;"                                                     NEW_LINE

    "    vec4 col;"                                                         NEW_LINE
    "    float d = roundedBox(p, vec2(roundedBoxWidth, roundedBoxHeight), radius);"           NEW_LINE//distance from rounded rect bounds

    "    if( hollow == false )"                                             NEW_LINE
    "    {"                                                                 NEW_LINE
    "        col = sqrt(mix(innerColor*innerColor, outerColor*outerColor, smoothstep(0., gradient, d ) ));"                                     NEW_LINE
    "    }"                                                                 NEW_LINE
    "    else"                                                              NEW_LINE
    "    {"                                                                 NEW_LINE
    "        if( abs(d) < gradient )"                                       NEW_LINE
    "        {"                                                             NEW_LINE
    "            if( d == 0. )"                                             NEW_LINE
    "            {"                                                         NEW_LINE
    "                col = innerColor; "                                    NEW_LINE  //purple
    "            }"                                                         NEW_LINE
    "            else"                                                      NEW_LINE
    "            {"                                                         NEW_LINE
    "                col = sqrt(mix(innerColor*innerColor, outerColor*outerColor, smoothstep(0., gradient, abs(d)) ));" NEW_LINE
    "            }"                                                         NEW_LINE
    "        }"                                                             NEW_LINE
    "        else"                                                          NEW_LINE
    "        {"                                                             NEW_LINE
    "            col = outerColor; //yellow"                                NEW_LINE
    "        }"                                                             NEW_LINE
    "    }"                                                                 NEW_LINE

//    "col.x = hsluv_fromLinear(col.x);"
//    "col.y = hsluv_fromLinear(col.y);"
//    "col.z = hsluv_fromLinear(col.z);"
//    "col.w = hsluv_fromLinear(col.w);"
    "    gl_FragColor = col;"                                               NEW_LINE
    "}";