119 lines
3.9 KiB
GLSL
119 lines
3.9 KiB
GLSL
/**
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* @file class1/deferred/aoUtil.glsl
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*
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* $LicenseInfo:firstyear=2007&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2007, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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uniform sampler2D noiseMap;
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uniform sampler2D depthMap;
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uniform float ssao_radius;
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uniform float ssao_max_radius;
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uniform float ssao_factor;
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uniform float ssao_factor_inv;
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uniform mat4 inv_proj;
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uniform vec2 screen_res;
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vec2 getScreenCoordinateAo(vec2 screenpos)
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{
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vec2 sc = screenpos.xy * 2.0;
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return sc - vec2(1.0, 1.0);
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}
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float getDepthAo(vec2 pos_screen)
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{
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float depth = texture(depthMap, pos_screen).r;
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return depth;
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}
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vec4 getPositionAo(vec2 pos_screen)
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{
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float depth = getDepthAo(pos_screen);
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vec2 sc = getScreenCoordinateAo(pos_screen);
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vec4 ndc = vec4(sc.x, sc.y, 2.0*depth-1.0, 1.0);
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vec4 pos = inv_proj * ndc;
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pos /= pos.w;
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pos.w = 1.0;
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return pos;
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}
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vec2 getKern(int i)
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{
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vec2 kern[8];
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// exponentially (^2) distant occlusion samples spread around origin
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kern[0] = vec2(-1.0, 0.0) * 0.125*0.125;
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kern[1] = vec2(1.0, 0.0) * 0.250*0.250;
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kern[2] = vec2(0.0, 1.0) * 0.375*0.375;
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kern[3] = vec2(0.0, -1.0) * 0.500*0.500;
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kern[4] = vec2(0.7071, 0.7071) * 0.625*0.625;
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kern[5] = vec2(-0.7071, -0.7071) * 0.750*0.750;
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kern[6] = vec2(-0.7071, 0.7071) * 0.875*0.875;
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kern[7] = vec2(0.7071, -0.7071) * 1.000*1.000;
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return kern[i] / screen_res;
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}
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//calculate decreases in ambient lighting when crowded out (SSAO)
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float calcAmbientOcclusion(vec4 pos, vec3 norm, vec2 pos_screen)
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{
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float ret = 1.0;
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vec3 pos_world = pos.xyz;
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vec2 noise_reflect = texture(noiseMap, pos_screen.xy * (screen_res / 128)).xy;
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float angle_hidden = 0.0;
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float points = 0;
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float scale = min(ssao_radius / -pos_world.z, ssao_max_radius);
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// it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations (unrolling?)
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for (int i = 0; i < 8; i++)
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{
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vec2 samppos_screen = pos_screen + scale * reflect(getKern(i), noise_reflect);
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vec3 samppos_world = getPositionAo(samppos_screen).xyz;
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vec3 diff = pos_world - samppos_world;
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float dist2 = dot(diff, diff);
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// assume each sample corresponds to an occluding sphere with constant radius, constant x-sectional area
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// --> solid angle shrinking by the square of distance
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//radius is somewhat arbitrary, can approx with just some constant k * 1 / dist^2
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//(k should vary inversely with # of samples, but this is taken care of later)
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float funky_val = (dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) ? 1.0 : 0.0;
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angle_hidden = angle_hidden + funky_val * min(1.0/dist2, ssao_factor_inv);
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// 'blocked' samples (significantly closer to camera relative to pos_world) are "no data", not "no occlusion"
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float diffz_val = (diff.z > -1.0) ? 1.0 : 0.0;
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points = points + diffz_val;
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}
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angle_hidden = min(ssao_factor*angle_hidden/points, 1.0);
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float points_val = (points > 0.0) ? 1.0 : 0.0;
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ret = (1.0 - (points_val * angle_hidden));
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ret = max(ret, 0.0);
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return min(ret, 1.0);
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}
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