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OpenSpace/shaders/PowerScaling/powerScalingMath.hglsl

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/*****************************************************************************************
* *
* OpenSpace *
* *
* Copyright (c) 2014 *
* *
* Permission is hereby granted, free of charge, to any person obtaining a copy of this *
* software and associated documentation files (the "Software"), to deal in the Software *
* without restriction, including without limitation the rights to use, copy, modify, *
* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to *
* permit persons to whom the Software is furnished to do so, subject to the following *
* conditions: *
* *
* The above copyright notice and this permission notice shall be included in all copies *
* or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, *
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A *
* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT *
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF *
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE *
* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
****************************************************************************************/
#ifndef POWERSCALING_MATH_HGLSL
#define POWERSCALING_MATH_HGLSL
const float k = 10.0;
const float FLT_MAX = 1e38; // Not max but large enough for the purpose
float log10(float x) {
return log(x) / log(10);
}
vec4 psc_normalization(vec4 v) {
vec4 v2 = v;
float l = length(v.xyz);
v2.xyz = v.xyz / l;
v2.w = v.w - log10(1.0/l);
return v2;
}
vec4 psc_addition(vec4 v1, vec4 v2) {
float ds = v2.w - v1.w;
if(ds >= 0) {
float p = pow(k,-ds);
return vec4(v1.x*p + v2.x, v1.y*p + v2.y, v1.z*p + v2.z, v2.w);
} else {
float p = pow(k,ds);
return vec4(v1.x + v2.x*p, v1.y + v2.y*p, v1.z + v2.z*p, v1.w);
}
}
vec4 z_normalization(vec4 v_in) {
vec4 v_out = v_in;
if(v_out.z > 0.0) {
v_out.z = 1;
} else if(v_out.z < 0.0) {
v_out.z = 1;
} else {
float tmp = max(max(abs(v_out.x), abs(v_out.y)),0);
if(tmp == 0.0)
v_out.s = FLT_MAX;
}
return v_out;
}
#endif