190 lines
6.2 KiB
GLSL
190 lines
6.2 KiB
GLSL
/* Copyright (c) 2014-2018, NVIDIA CORPORATION. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of NVIDIA CORPORATION nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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//-
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// This utility compresses a normal(x,y,z) to a uint and decompresses it
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#define C_Stack_Max 3.402823466e+38f
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uint CompressUnitVec(vec3 nv)
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{
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// map to octahedron and then flatten to 2D (see 'Octahedron Environment Maps' by Engelhardt & Dachsbacher)
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if((nv.x < C_Stack_Max) && !isinf(nv.x))
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{
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const float d = 32767.0f / (abs(nv.x) + abs(nv.y) + abs(nv.z));
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int x = int(roundEven(nv.x * d));
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int y = int(roundEven(nv.y * d));
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if(nv.z < 0.0f)
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{
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const int maskx = x >> 31;
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const int masky = y >> 31;
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const int tmp = 32767 + maskx + masky;
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const int tmpx = x;
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x = (tmp - (y ^ masky)) ^ maskx;
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y = (tmp - (tmpx ^ maskx)) ^ masky;
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}
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uint packed = (uint(y + 32767) << 16) | uint(x + 32767);
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if(packed == ~0u)
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return ~0x1u;
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return packed;
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}
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else
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{
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return ~0u;
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}
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}
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float ShortToFloatM11(const int v) // linearly maps a short 32767-32768 to a float -1-+1 //!! opt.?
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{
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return (v >= 0) ? (uintBitsToFloat(0x3F800000u | (uint(v) << 8)) - 1.0f) :
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(uintBitsToFloat((0x80000000u | 0x3F800000u) | (uint(-v) << 8)) + 1.0f);
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}
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vec3 DecompressUnitVec(uint packed)
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{
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if(packed != ~0u) // sanity check, not needed as isvalid_unit_vec is called earlier
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{
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int x = int(packed & 0xFFFFu) - 32767;
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int y = int(packed >> 16) - 32767;
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const int maskx = x >> 31;
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const int masky = y >> 31;
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const int tmp0 = 32767 + maskx + masky;
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const int ymask = y ^ masky;
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const int tmp1 = tmp0 - (x ^ maskx);
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const int z = tmp1 - ymask;
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float zf;
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if(z < 0)
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{
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x = (tmp0 - ymask) ^ maskx;
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y = tmp1 ^ masky;
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zf = uintBitsToFloat((0x80000000u | 0x3F800000u) | (uint(-z) << 8)) + 1.0f;
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}
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else
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{
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zf = uintBitsToFloat(0x3F800000u | (uint(z) << 8)) - 1.0f;
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}
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return normalize(vec3(ShortToFloatM11(x), ShortToFloatM11(y), zf));
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}
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else
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{
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return vec3(C_Stack_Max);
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}
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}
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//-------------------------------------------------------------------------------------------------
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// Avoiding self intersections (see Ray Tracing Gems, Ch. 6)
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//
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vec3 OffsetRay(in vec3 p, in vec3 n)
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{
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const float intScale = 256.0f;
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const float floatScale = 1.0f / 65536.0f;
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const float origin = 1.0f / 32.0f;
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ivec3 of_i = ivec3(intScale * n.x, intScale * n.y, intScale * n.z);
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vec3 p_i = vec3(intBitsToFloat(floatBitsToInt(p.x) + ((p.x < 0) ? -of_i.x : of_i.x)),
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intBitsToFloat(floatBitsToInt(p.y) + ((p.y < 0) ? -of_i.y : of_i.y)),
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intBitsToFloat(floatBitsToInt(p.z) + ((p.z < 0) ? -of_i.z : of_i.z)));
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return vec3(abs(p.x) < origin ? p.x + floatScale * n.x : p_i.x, //
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abs(p.y) < origin ? p.y + floatScale * n.y : p_i.y, //
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abs(p.z) < origin ? p.z + floatScale * n.z : p_i.z);
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}
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//////////////////////////// AO //////////////////////////////////////
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#define EPS 0.05
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const float M_PI = 3.141592653589;
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void ComputeDefaultBasis(const vec3 normal, out vec3 x, out vec3 y)
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{
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// ZAP's default coordinate system for compatibility
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vec3 z = normal;
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const float yz = -z.y * z.z;
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y = normalize(((abs(z.z) > 0.99999f) ? vec3(-z.x * z.y, 1.0f - z.y * z.y, yz) :
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vec3(-z.x * z.z, yz, 1.0f - z.z * z.z)));
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x = cross(y, z);
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}
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//-------------------------------------------------------------------------------------------------
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// Random
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//-------------------------------------------------------------------------------------------------
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// Generate a random unsigned int from two unsigned int values, using 16 pairs
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// of rounds of the Tiny Encryption Algorithm. See Zafar, Olano, and Curtis,
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// "GPU Random Numbers via the Tiny Encryption Algorithm"
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uint tea(uint val0, uint val1)
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{
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uint v0 = val0;
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uint v1 = val1;
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uint s0 = 0;
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for(uint n = 0; n < 16; n++)
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{
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s0 += 0x9e3779b9;
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v0 += ((v1 << 4) + 0xa341316c) ^ (v1 + s0) ^ ((v1 >> 5) + 0xc8013ea4);
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v1 += ((v0 << 4) + 0xad90777d) ^ (v0 + s0) ^ ((v0 >> 5) + 0x7e95761e);
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}
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return v0;
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}
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uvec2 pcg2d(uvec2 v)
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{
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v = v * 1664525u + 1013904223u;
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v.x += v.y * 1664525u;
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v.y += v.x * 1664525u;
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v = v ^ (v >> 16u);
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v.x += v.y * 1664525u;
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v.y += v.x * 1664525u;
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v = v ^ (v >> 16u);
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return v;
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}
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// Generate a random unsigned int in [0, 2^24) given the previous RNG state
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// using the Numerical Recipes linear congruential generator
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uint lcg(inout uint prev)
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{
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uint LCG_A = 1664525u;
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uint LCG_C = 1013904223u;
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prev = (LCG_A * prev + LCG_C);
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return prev & 0x00FFFFFF;
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}
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// Generate a random float in [0, 1) given the previous RNG state
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float rnd(inout uint seed)
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{
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return (float(lcg(seed)) / float(0x01000000));
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}
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