forked from Rowland/EG
96 lines
3.1 KiB
GLSL
96 lines
3.1 KiB
GLSL
/**
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*
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* RenderPipeline
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*
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* Copyright (c) 2014-2016 tobspr <tobias.springer1@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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*/
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/*
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UE4AO - Unreal Engine 4 AO
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This is an ambient occlusion technique proposed by Unreal Engine. It is very
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similar to Alchemy AO, but uses paired samples to approximate the average
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unocluded vector.
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*/
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const float sample_radius = GET_SETTING(ao, ue4ao_sample_radius);
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const float max_distance = GET_SETTING(ao, ue4ao_max_distance);
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float accum = 0.0;
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float accum_count = 0.0;
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vec2 offset_scale = pixel_size * sample_radius * kernel_scale * 0.4;
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START_ITERATE_SEQUENCE(ao, ue4ao_sample_sequence, vec2 offset)
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offset = mix(offset, noise_vec.xy, 0.3);
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vec2 offcoord = offset * offset_scale;
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// Get offset coordinates
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vec2 texc_a = texcoord + offcoord;
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vec2 texc_b = texcoord - offcoord;
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// Get view position at that offsets
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vec3 off_pos_a = get_view_pos_at(texc_a);
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vec3 off_pos_b = get_view_pos_at(texc_b);
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// Get the vector s-p to that sample positions
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vec3 sample_vec_a = normalize(off_pos_a - pixel_view_pos);
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vec3 sample_vec_b = normalize(off_pos_b - pixel_view_pos);
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// Get distances
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float dist_a = distance(off_pos_a, pixel_view_pos) / max_distance;
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float dist_b = distance(off_pos_b, pixel_view_pos) / max_distance;
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// Check if the samples are valid
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float valid_a = step(dist_a - 1, 0.0);
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float valid_b = step(dist_b - 1, 0.0);
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float angle_a = max(0, dot(sample_vec_a, pixel_view_normal));
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float angle_b = max(0, dot(sample_vec_b, pixel_view_normal));
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// TODO: Avoid branching by every means
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if (valid_a != valid_b) {
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angle_a = mix(-angle_b, angle_a, valid_a);
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angle_b = mix(angle_a, -angle_b, valid_b);
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dist_a = mix(dist_b, dist_a, valid_a);
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dist_b = mix(dist_a, dist_b, valid_b);
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}
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// In case any sample is valid
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if (valid_a > 0.5 || valid_b > 0.5) {
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accum += (angle_a+angle_b) * 0.25 * (2 - (dist_a+dist_b));
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accum_count += 1.0;
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} else {
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accum_count += 0.5;
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}
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END_ITERATE_SEQUENCE();
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accum /= max(1.0, accum_count);
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result = 1 - accum;
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