101 lines
3.8 KiB
GLSL
101 lines
3.8 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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SSVO - Screen Space Volumetric Obscurance
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This algorithm casts rays to a sphere arround the current point in view space,
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and approximates the spheres volume by using line intetrals. The percentage
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of the spheres volume is then used to compute AO.
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*/
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vec2 sphere_radius = GET_SETTING(ao, ssvo_sphere_radius) * pixel_size;
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float max_depth_diff = GET_SETTING(ao, ssvo_max_distance) / kernel_scale;
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float accum = 0.0;
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float pixel_linz = get_linear_z_from_z(pixel_depth);
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START_ITERATE_SEQUENCE(ao, ssvo_sequence, vec2 offset)
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offset = mix(offset, noise_vec.xy, 0.3);
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vec2 offc = offset * sphere_radius * 5.0 * kernel_scale;
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// Use paired samples, this enables us to hide depth buffer discontinuities
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vec2 offcoord_a = texcoord + offc;
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vec2 offcoord_b = texcoord - offc;
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// Compute the sphere height at the sample location
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float sphere_height = sqrt(1 - dot(offset, offset));
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// Get the depth at the sample locations, also
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// make the depth linear, this enables us to compare them better
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float depth_linz_a = get_linear_depth_at(offcoord_a);
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float depth_linz_b = get_linear_depth_at(offcoord_b);
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// Clamp both differences to the maximum depth difference
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float diff_a = (pixel_linz - depth_linz_a) / max_depth_diff;
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float diff_b = (pixel_linz - depth_linz_b) / max_depth_diff;
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// Compute the line integrals of boths, this is simply the height of the
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// line divided by the sphere height. However, we need to substract the
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// sphere height once, since we didn't start at the sphere top, but at
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// the sphere mid (since we took the depth of point p which is the center
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// of the sphere).
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float volume_a = (sphere_height - diff_a) / (2.0 * sphere_height);
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float volume_b = (sphere_height - diff_b) / (2.0 * sphere_height);
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// Check if the volumes are valid
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bool valid_a = diff_a <= sphere_height && diff_a >= -sphere_height;
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bool valid_b = diff_b <= sphere_height && diff_b >= -sphere_height;
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// In case either the first or second sample is valid, we can weight them
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if (valid_a || valid_b) {
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// Because we use paired samples, we can easily account for discontinuities:
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// If a is invalid, we can take the inverse of b as value for a, and vice-versa.
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// This works out quite well, even if not mathematically correct.
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accum += valid_a ? volume_a : 1 - volume_b;
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accum += valid_b ? volume_b : 1 - volume_a;
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// In case both samples are invalid, theres nothing we can do. Just increase
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// the integral in this case.
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} else {
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accum += 1.0;
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}
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END_ITERATE_SEQUENCE();
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NORMALIZE_SEQUENCE(ao, ssvo_sequence, accum);
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result = accum;
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