Thermal effect on infrared camera image (not real)

thermal_effect.glsl

out vec4 fragColor;

uniform float saturation;
uniform float brightness;
uniform float phase;

const float MIN_HUE = 0.0;
const float MAX_HUE = 0.66;
const float PHASE = 0.25;

vec3 hsb2rgb( in vec3 c )
{
    vec3 rgb = clamp(abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),
                             6.0)-3.0)-1.0,
							 0.0,
							 1.0 );
    rgb = rgb*rgb*(3.0-2.0*rgb);
    return c.z * mix( vec3(1.0), rgb, c.y);
}

void main()
{
    vec4 color = texture(sTD2DInputs[0], vUV.st);
    float src_color = color.r;
    src_color *= MAX_HUE;
    src_color += clamp(phase, 0.0, 1.0) * PHASE;
    float h = clamp(MAX_HUE - src_color, MIN_HUE, MAX_HUE);
    float s = clamp(saturation, 0.0, 1.0);
    float v = clamp(brightness, 0.0, 1.0);
    color.rgb = hsb2rgb(vec3(h, s, v));
    fragColor = TDOutputSwizzle(color);
}