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HDR: Fix "floating" shadows in Screen Space Shadows

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This commit is contained in:
Fernando García Liñán 2023-10-04 01:56:47 +02:00
parent d65228be6c
commit e12afa0a7d
7 changed files with 269 additions and 44 deletions
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40
Effects/HDR/shading-opaque.eff
View file

@ -20,6 +20,21 @@
<show-shadow-cascades>
<use>/sim/rendering/hdr/debug/show-shadow-cascades</use>
</show-shadow-cascades>
<normal-bias>
<use>/sim/rendering/hdr/shadows/normal-bias</use>
</normal-bias>
<sss-enabled>
<use>/sim/rendering/hdr/shadows/sss-enabled</use>
</sss-enabled>
<sss-step-count>
<use>/sim/rendering/hdr/shadows/sss-step-count</use>
</sss-step-count>
<sss-max-distance>
<use>/sim/rendering/hdr/shadows/sss-max-distance</use>
</sss-max-distance>
<sss-depth-bias>
<use>/sim/rendering/hdr/shadows/sss-depth-bias</use>
</sss-depth-bias>
<!-- exposure.glsl -->
<exposure-compensation>
<use>/sim/rendering/hdr/exposure-compensation</use>
@ -111,6 +126,31 @@
<type>bool</type>
<value><use>show-shadow-cascades</use></value>
</uniform>
<uniform>
<name>normal_bias</name>
<type>float</type>
<value><use>normal-bias</use></value>
</uniform>
<uniform>
<name>sss_enabled</name>
<type>bool</type>
<value><use>sss-enabled</use></value>
</uniform>
<uniform>
<name>sss_step_count</name>
<type>int</type>
<value><use>sss-step-count</use></value>
</uniform>
<uniform>
<name>sss_max_distance</name>
<type>float</type>
<value><use>sss-max-distance</use></value>
</uniform>
<uniform>
<name>sss_depth_bias</name>
<type>float</type>
<value><use>sss-depth-bias</use></value>
</uniform>
<!-- ibl.glsl -->
<uniform>
<name>dfg_tex</name>

61
Effects/model-combined-transparent.eff
View file

@ -7,6 +7,42 @@ It's kept for backwards compatibility and should not be used on new projects.
<name>Effects/model-combined-transparent</name>
<inherits-from>Effects/model-combined</inherits-from>
<parameters>
<!-- ibl.glsl -->
<texture n="8">
<image>Textures/PBR/dfg_lut.dds</image>
<type>2d</type>
<filter>linear</filter>
<mag-filter>linear</mag-filter>
<wrap-s>clamp-to-edge</wrap-s>
<wrap-t>clamp-to-edge</wrap-t>
<internal-format>normalized</internal-format>
</texture>
<!-- shadows.glsl -->
<show-shadow-cascades>
<use>/sim/rendering/hdr/debug/show-shadow-cascades</use>
</show-shadow-cascades>
<normal-bias>
<use>/sim/rendering/hdr/shadows/normal-bias</use>
</normal-bias>
<sss-enabled>
<use>/sim/rendering/hdr/shadows/sss-enabled</use>
</sss-enabled>
<sss-step-count>
<use>/sim/rendering/hdr/shadows/sss-step-count</use>
</sss-step-count>
<sss-max-distance>
<use>/sim/rendering/hdr/shadows/sss-max-distance</use>
</sss-max-distance>
<sss-depth-bias>
<use>/sim/rendering/hdr/shadows/sss-depth-bias</use>
</sss-depth-bias>
<!-- exposure.glsl -->
<exposure-compensation>
<use>/sim/rendering/hdr/exposure-compensation</use>
</exposure-compensation>
</parameters>
<technique n="107">
<scheme>hdr-geometry</scheme>
</technique>
@ -87,6 +123,31 @@ It's kept for backwards compatibility and should not be used on new projects.
<type>bool</type>
<value><use>show-shadow-cascades</use></value>
</uniform>
<uniform>
<name>normal_bias</name>
<type>float</type>
<value><use>normal-bias</use></value>
</uniform>
<uniform>
<name>sss_enabled</name>
<type>bool</type>
<value><use>sss-enabled</use></value>
</uniform>
<uniform>
<name>sss_step_count</name>
<type>int</type>
<value><use>sss-step-count</use></value>
</uniform>
<uniform>
<name>sss_max_distance</name>
<type>float</type>
<value><use>sss-max-distance</use></value>
</uniform>
<uniform>
<name>sss_depth_bias</name>
<type>float</type>
<value><use>sss-depth-bias</use></value>
</uniform>
<!-- ibl.glsl -->
<uniform>
<name>dfg_tex</name>

44
Effects/model-pbr-transparent.eff
View file

@ -18,6 +18,25 @@
<wrap-t>clamp-to-edge</wrap-t>
<internal-format>normalized</internal-format>
</texture>
<!-- shadows.glsl -->
<show-shadow-cascades>
<use>/sim/rendering/hdr/debug/show-shadow-cascades</use>
</show-shadow-cascades>
<normal-bias>
<use>/sim/rendering/hdr/shadows/normal-bias</use>
</normal-bias>
<sss-enabled>
<use>/sim/rendering/hdr/shadows/sss-enabled</use>
</sss-enabled>
<sss-step-count>
<use>/sim/rendering/hdr/shadows/sss-step-count</use>
</sss-step-count>
<sss-max-distance>
<use>/sim/rendering/hdr/shadows/sss-max-distance</use>
</sss-max-distance>
<sss-depth-bias>
<use>/sim/rendering/hdr/shadows/sss-depth-bias</use>
</sss-depth-bias>
<!-- exposure.glsl -->
<exposure-compensation>
<use>/sim/rendering/hdr/exposure-compensation</use>
@ -169,6 +188,31 @@
<type>bool</type>
<value><use>show-shadow-cascades</use></value>
</uniform>
<uniform>
<name>normal_bias</name>
<type>float</type>
<value><use>normal-bias</use></value>
</uniform>
<uniform>
<name>sss_enabled</name>
<type>bool</type>
<value><use>sss-enabled</use></value>
</uniform>
<uniform>
<name>sss_step_count</name>
<type>int</type>
<value><use>sss-step-count</use></value>
</uniform>
<uniform>
<name>sss_max_distance</name>
<type>float</type>
<value><use>sss-max-distance</use></value>
</uniform>
<uniform>
<name>sss_depth_bias</name>
<type>float</type>
<value><use>sss-depth-bias</use></value>
</uniform>
<!-- ibl.glsl -->
<uniform>
<name>dfg_tex</name>

44
Effects/model-transparent.eff
View file

@ -14,6 +14,25 @@
<wrap-t>clamp-to-edge</wrap-t>
<internal-format>normalized</internal-format>
</texture>
<!-- shadows.glsl -->
<show-shadow-cascades>
<use>/sim/rendering/hdr/debug/show-shadow-cascades</use>
</show-shadow-cascades>
<normal-bias>
<use>/sim/rendering/hdr/shadows/normal-bias</use>
</normal-bias>
<sss-enabled>
<use>/sim/rendering/hdr/shadows/sss-enabled</use>
</sss-enabled>
<sss-step-count>
<use>/sim/rendering/hdr/shadows/sss-step-count</use>
</sss-step-count>
<sss-max-distance>
<use>/sim/rendering/hdr/shadows/sss-max-distance</use>
</sss-max-distance>
<sss-depth-bias>
<use>/sim/rendering/hdr/shadows/sss-depth-bias</use>
</sss-depth-bias>
<!-- exposure.glsl -->
<exposure-compensation>
<use>/sim/rendering/hdr/exposure-compensation</use>
@ -100,6 +119,31 @@
<type>bool</type>
<value><use>show-shadow-cascades</use></value>
</uniform>
<uniform>
<name>normal_bias</name>
<type>float</type>
<value><use>normal-bias</use></value>
</uniform>
<uniform>
<name>sss_enabled</name>
<type>bool</type>
<value><use>sss-enabled</use></value>
</uniform>
<uniform>
<name>sss_step_count</name>
<type>int</type>
<value><use>sss-step-count</use></value>
</uniform>
<uniform>
<name>sss_max_distance</name>
<type>float</type>
<value><use>sss-max-distance</use></value>
</uniform>
<uniform>
<name>sss_depth_bias</name>
<type>float</type>
<value><use>sss-depth-bias</use></value>
</uniform>
<!-- ibl.glsl -->
<uniform>
<name>dfg_tex</name>

9
Shaders/HDR/math.glsl
View file

@ -34,3 +34,12 @@ float pow5(float x) {
float x2 = x*x;
return x2 * x2 * x;
}
/*
* Random number between 0 and 1, using interleaved gradient noise.
* uv must not be normalized.
*/
float interleaved_gradient_noise(vec2 uv) {
const vec3 m = vec3(0.06711056, 0.00583715, 52.9829189);
return fract(m.z * fract(dot(uv, m.xy)));
}

108
Shaders/HDR/shadows.glsl
View file

@ -3,30 +3,30 @@
uniform sampler2DShadow shadow_tex;
uniform sampler2D depth_tex; // For Screen Space Shadows
uniform bool debug_shadow_cascades;
uniform mat4 fg_LightMatrix_csm0;
uniform mat4 fg_LightMatrix_csm1;
uniform mat4 fg_LightMatrix_csm2;
uniform mat4 fg_LightMatrix_csm3;
const float NORMAL_BIAS = 0.02;
uniform bool debug_shadow_cascades;
uniform float normal_bias;
uniform bool sss_enabled;
uniform int sss_step_count;
uniform float sss_max_distance;
uniform float sss_depth_bias;
const float BAND_SIZE = 0.1;
const vec2 BAND_BOTTOM_LEFT = vec2(BAND_SIZE);
const vec2 BAND_TOP_RIGHT = vec2(1.0 - BAND_SIZE);
// Ideally these should be passed as an uniform, but we don't support uniform
// arrays yet
const vec2 uv_shifts[4] = vec2[4](
const vec2 UV_SHIFTS[4] = vec2[4](
vec2(0.0, 0.0), vec2(0.5, 0.0),
vec2(0.0, 0.5), vec2(0.5, 0.5));
const vec2 uv_factor = vec2(0.5, 0.5);
const vec2 UV_FACTOR = vec2(0.5, 0.5);
// Screen Space Shadows parameters
const float SSS_THICKNESS = 0.1;
const uint SSS_NUM_STEPS = 16u;
const float SSS_MAX_DISTANCE = 0.05;
const vec3 DITHER_MAGIC = vec3(0.06711056, 0.00583715, 52.9829189);
// math.glsl
float saturate(float x);
float interleaved_gradient_noise(vec2 uv);
float sample_shadow_map(vec2 coord, vec2 offset, float depth)
{
@ -77,7 +77,7 @@ float sample_optimized_PCF(vec4 pos, vec2 map_size)
float sample_cascade(vec4 P, vec2 shift, vec2 map_size)
{
vec4 pos = P;
pos.xy *= uv_factor;
pos.xy *= UV_FACTOR;
pos.xy += shift;
return sample_optimized_PCF(pos, map_size);
}
@ -113,56 +113,76 @@ bool is_inside_band(vec4 P)
vec4 get_light_space_position(vec3 P, vec3 N, float NdotL, mat4 light_matrix)
{
float sin_theta = sqrt(1.0 - NdotL * NdotL);
vec3 offset_pos = P + N * (sin_theta * NORMAL_BIAS);
vec3 offset_pos = P + N * (sin_theta * normal_bias);
return light_matrix * vec4(offset_pos, 1.0);
}
/*
* Screen Space Shadows
*
* Implementation mostly based on:
* https://panoskarabelas.com/posts/screen_space_shadows/
* Marching done in screen space instead of in view space.
*
* Marching done in screen space instead of in view space to save us from doing
* matrix multiplications inside the ray marching loop.
*
* Tolerance trick to avoid "floating shadows" based on Filament.
*/
float get_contact_shadow(vec3 P, vec3 L, mat4 projection_matrix)
{
// Ray start and end points in view space
if (!sss_enabled)
return 1.0;
vec3 vs_ray_start = P;
vec3 vs_ray_end = vs_ray_start + L * SSS_MAX_DISTANCE;
// To clip space
vec3 vs_ray_end = vs_ray_start + L * sss_max_distance;
vec4 cs_ray_start = projection_matrix * vec4(vs_ray_start, 1.0);
vec4 cs_ray_end = projection_matrix * vec4(vs_ray_end, 1.0);
// Perspective divide
vec3 ray_start = cs_ray_start.xyz / cs_ray_start.w;
vec3 ray_end = cs_ray_end.xyz / cs_ray_end.w;
vec4 cs_view_ray_end = cs_ray_start + projection_matrix
* vec4(0.0, 0.0, sss_max_distance, 0.0);
cs_ray_start /= cs_ray_start.w;
cs_ray_end /= cs_ray_end.w;
cs_view_ray_end /= cs_view_ray_end.w;
// From [-1,1] to [0,1] to sample directly from textures
ray_start = ray_start * 0.5 + 0.5;
ray_end = ray_end * 0.5 + 0.5;
// z is also mapped to [0,1] to compare it with the depth buffer
vec3 ray_start = cs_ray_start.xyz * 0.5 + 0.5;
vec3 ray_end = cs_ray_end.xyz * 0.5 + 0.5;
vec3 ray_dir = ray_end - ray_start;
vec3 ray = ray_end - ray_start;
float t_max = length(ray);
vec3 ray_dir = ray / t_max;
float dither = fract(DITHER_MAGIC.z * fract(dot(gl_FragCoord.xy, DITHER_MAGIC.xy)));
float dt = 1.0 / float(SSS_NUM_STEPS);
float t = dt * dither + dt;
float dt = t_max / float(sss_step_count);
float dither = interleaved_gradient_noise(gl_FragCoord.xy);
float tolerance = abs(cs_view_ray_end.z - cs_ray_start.z) / float(sss_step_count);
float shadow = 0.0;
for (uint i = 0u; i < SSS_NUM_STEPS; ++i) {
vec3 sample_pos = ray_start + ray_dir * t;
// Reversed depth buffer, invert it
float sample_depth = 1.0 - texture(depth_tex, sample_pos.xy).r;
float dz = sample_pos.z - sample_depth;
if (dz > 0.00001 && dz < SSS_THICKNESS) {
for (int i = 0; i < sss_step_count; ++i) {
float t = (float(i) + dither) * dt;
vec3 x_t = ray_start + ray_dir * t;
// Sample the depth buffer. It's reversed, so invert it
float z = 1.0 - texture(depth_tex, x_t.xy).r;
// Depth difference between the current ray sample depth and the actual
// camera depth contained in the depth buffer.
float dz = x_t.z - z - sss_depth_bias;
if (abs(tolerance - dz) < tolerance) {
// We are in shadow
shadow = 1.0;
vec2 screen_fade = smoothstep(vec2(0.0), vec2(0.07), sample_pos.xy)
- smoothstep(vec2(0.93), vec2(1.0), sample_pos.xy);
// Fade the shadows towards the edges of the screen
vec2 screen_fade =
smoothstep(vec2(0.0), vec2(0.07), x_t.xy) -
smoothstep(vec2(0.93), vec2(1.0), x_t.xy);
shadow *= screen_fade.x * screen_fade.y;
break;
}
t += dt;
}
return 1.0 - shadow;
return (1.0 - shadow);
}
/*
@ -172,7 +192,7 @@ float get_contact_shadow(vec3 P, vec3 L, mat4 projection_matrix)
*/
float get_shadowing(vec3 P, vec3 N, vec3 L)
{
float NdotL = clamp(dot(N, L), 0.0, 1.0);
float NdotL = saturate(dot(N, L));
vec4 ls_P[4];
ls_P[0] = get_light_space_position(P, N, NdotL, fg_LightMatrix_csm0);
@ -195,7 +215,7 @@ float get_shadowing(vec3 P, vec3 N, vec3 L)
BAND_BOTTOM_LEFT,
BAND_TOP_RIGHT);
float cascade0 = sample_cascade(ls_P[i],
uv_shifts[i],
UV_SHIFTS[i],
map_size);
float cascade1;
if (i == 3) {
@ -203,7 +223,7 @@ float get_shadowing(vec3 P, vec3 N, vec3 L)
cascade1 = 1.0;
} else {
cascade1 = sample_cascade(ls_P[i+1],
uv_shifts[i+1],
UV_SHIFTS[i+1],
map_size);
}
visibility = mix(cascade0, cascade1, blend);
@ -212,13 +232,13 @@ float get_shadowing(vec3 P, vec3 N, vec3 L)
// we skip the blending to avoid the performance cost
// of sampling the shadow map twice.
visibility = sample_cascade(ls_P[i],
uv_shifts[i],
UV_SHIFTS[i],
map_size);
}
break;
}
}
visibility = clamp(visibility, 0.0, 1.0);
visibility = saturate(visibility);
return visibility;
}
@ -228,7 +248,7 @@ vec3 debug_shadow_color(vec3 color, vec3 P, vec3 N, vec3 L)
if (!debug_shadow_cascades)
return color;
float NdotL = clamp(dot(N, L), 0.0, 1.0);
float NdotL = saturate(dot(N, L));
vec4 ls_P[4];
ls_P[0] = get_light_space_position(P, N, NdotL, fg_LightMatrix_csm0);

7
defaults.xml
View file

@ -559,6 +559,13 @@ Started September 2000 by David Megginson, david@megginson.com
<enabled type="bool" userarchive="y">true</enabled>
<world-radius type="float">0.2</world-radius>
</ambient-occlusion>
<shadows>
<normal-bias type="float">0.02</normal-bias>
<sss-enabled type="bool" userarchive="y">true</sss-enabled>
<sss-step-count type="int">32</sss-step-count>
<sss-max-distance type="float">0.2</sss-max-distance>
<sss-depth-bias type="float">0.00001</sss-depth-bias>
</shadows>
<debug>
<display-ev100 type="bool">false</display-ev100>
<show-gbuffer type="bool">false</show-gbuffer>