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/*
* Tuxánci 2 - A first person shooter
* Copyright (C) 2025-2026 Connor Thomson
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
struct light_uniforms {
float3 direction;
float shadow_texel_size;
float shadow_minimum_bias;
float shadow_maximum_bias;
float shadow_strength;
float shadow_penumbra_scale;
};
[[vk::binding(0, 3)]]
ConstantBuffer<light_uniforms> light : register(b0, space3);
[[vk::binding(0, 2)]]
Sampler2DShadow shadow_map : register(t0, space2);
[[vk::binding(1, 2)]]
Sampler2D<float> shadow_depth_map : register(t1, space2);
struct FSInput {
float3 normal : TEXCOORD0;
float3 world_position : TEXCOORD1;
float3 camera_position : TEXCOORD2;
float4 light_space_position : TEXCOORD3;
};
struct FSOutput {
float4 out_color : SV_Target0;
};
static const float ambient_strength = 0.22;
static const float diffuse_strength = 0.78;
static const float specular_strength = 0.6;
static const float shininess = 32.0;
static const int shadow_blocker_sample_count = 32;
static const int shadow_pcf_sample_count = 64;
static const float shadow_maximum_search_uv = 0.02;
static const float shadow_minimum_filter_texels = 1.5;
static const float shadow_maximum_filter_uv = 0.02;
static const float2 blocker_search_disk[shadow_blocker_sample_count] = {
float2( 0.44011213, -0.38478364),
float2(-0.93881893, 0.28433844),
float2( 0.29851448, 0.91473036),
float2(-0.56853028, -0.74873636),
float2( 0.92702072, 0.34599034),
float2(-0.17203432, 0.12048409),
float2(-0.40881620, 0.87902032),
float2( 0.11214125, -0.97011162),
float2( 0.35807629, 0.34593269),
float2(-0.93515467, -0.30090412),
float2( 0.96965589, -0.21669445),
float2(-0.12747712, -0.42799143),
float2(-0.04160416, 0.58750344),
float2(-0.50661284, -0.18463137),
float2(-0.49591186, 0.43573011),
float2( 0.69214410, 0.71546306),
float2( 0.58762817, -0.78906213),
float2( 0.60529434, -0.00157846),
float2( 0.18530521, -0.07537744),
float2(-0.06393139, 0.98782194),
float2(-0.24668936, -0.92075575),
float2( 0.81235073, -0.52916214),
float2( 0.18896697, -0.62996998),
float2(-0.71415530, 0.69260619),
float2(-0.65167829, 0.11466757),
float2(-0.65839165, -0.45386823),
float2( 0.40773627, 0.63990787),
float2(-0.99945967, -0.01288785),
float2( 0.06793334, 0.29985044),
float2( 0.88601041, 0.06665496),
float2( 0.63692110, 0.42919088),
float2(-0.38553272, -0.52927284),
};
static const float2 pcf_filter_disk[shadow_pcf_sample_count] = {
float2( 0.32558563, -0.24988839),
float2(-0.98541266, 0.16930865),
float2( 0.09145512, 0.89445213),
float2(-0.54480597, -0.82331975),
float2( 0.86243144, 0.42877010),
float2( 0.19152898, -0.98054135),
float2(-0.24839078, 0.19012049),
float2(-0.58789047, 0.78475191),
float2( 0.97505840, -0.19006157),
float2( 0.30273086, 0.33427269),
float2(-0.60614320, -0.24764520),
float2( 0.64000315, -0.68394018),
float2(-0.12301224, -0.53311522),
float2( 0.51234899, 0.75192892),
float2( 0.64313826, 0.06972717),
float2(-0.19284146, 0.60355651),
float2(-0.62280056, 0.36318874),
float2(-0.18834340, -0.95691492),
float2(-0.04911758, -0.13578936),
float2(-0.82927681, -0.54621998),
float2( 0.27020206, -0.61902601),
float2(-0.98076941, -0.18488425),
float2(-0.26883836, 0.96108127),
float2( 0.66283184, -0.32922370),
float2( 0.98983969, 0.13429859),
float2(-0.44329948, -0.53094113),
float2(-0.54192541, 0.06588807),
float2( 0.14739192, 0.59331660),
float2( 0.04982322, 0.14943985),
float2(-0.31222249, -0.26794820),
float2( 0.56008364, 0.46637058),
float2(-0.81663912, 0.57351727),
float2( 0.32731617, 0.05812120),
float2( 0.85294944, -0.52194453),
float2( 0.44306862, -0.87673132),
float2( 0.03380403, -0.76031090),
float2( 0.08711519, -0.36824602),
float2(-0.04387798, 0.39043461),
float2(-0.44689900, 0.54474622),
float2(-0.79730201, -0.01361312),
float2( 0.34065561, 0.93312502),
float2(-0.28571328, -0.73045171),
float2( 0.74645565, 0.64790973),
float2( 0.47432929, -0.49756161),
float2(-0.32838125, -0.02568294),
float2( 0.49288123, -0.09977098),
float2( 0.51299973, 0.24791173),
float2( 0.75389572, -0.12623179),
float2(-0.84467634, 0.34163260),
float2(-0.36987966, 0.76150517),
float2(-0.27850542, 0.40472485),
float2(-0.10969806, 0.80499616),
float2(-0.81179020, -0.32586517),
float2( 0.17068056, -0.09060725),
float2( 0.36889045, 0.58095936),
float2( 0.79213670, 0.22321366),
float2(-0.62388309, -0.63161735),
float2(-0.45122724, 0.24914915),
float2(-0.11527424, -0.33262249),
float2(-0.71985451, 0.17533603),
float2( 0.07976847, -0.56354086),
float2(-0.64407590, -0.43844161),
float2( 0.25012793, 0.75807218),
float2(-0.13113449, 0.03615541),
};
float find_blocker(float2 uv, float reference, float search_radius, out float blocker_depth) {
float blockers = 0.0;
blocker_depth = 0.0;
for (int index = 0; index < shadow_blocker_sample_count; index++) {
float depth = shadow_depth_map.SampleLevel(uv + blocker_search_disk[index] * search_radius, 0.0);
if (depth < reference) {
blocker_depth += depth;
blockers += 1.0;
}
}
if (blockers > 0.0) {
blocker_depth /= blockers;
}
return blockers;
}
float penumbra_size(float reference, float blocker_depth) {
return light.shadow_penumbra_scale * (reference - blocker_depth);
}
float pcf_filter(float2 uv, float reference, float filter_radius) {
float visibility = 0.0;
for (int index = 0; index < shadow_pcf_sample_count; index++) {
visibility += shadow_map.SampleCmpLevelZero(uv + pcf_filter_disk[index] * filter_radius, reference);
}
return visibility / float(shadow_pcf_sample_count);
}
float shadow_visibility(float4 light_space_position, float normal_dot_light) {
float3 projected = light_space_position.xyz / light_space_position.w;
if (projected.z < 0.0 || projected.z > 1.0) {
return 1.0;
}
float2 uv = float2(0.5 + 0.5 * projected.x, 0.5 - 0.5 * projected.y);
if (any(uv < 0.0) || any(uv > 1.0)) {
return 1.0;
}
float bias = max(light.shadow_maximum_bias * (1.0 - normal_dot_light), light.shadow_minimum_bias);
float reference = projected.z - bias;
float search_radius = clamp(light.shadow_penumbra_scale * reference, light.shadow_texel_size, shadow_maximum_search_uv);
float blocker_depth;
if (find_blocker(uv, reference, search_radius, blocker_depth) == 0.0) {
return 1.0;
}
float filter_radius = clamp(penumbra_size(reference, blocker_depth), shadow_minimum_filter_texels * light.shadow_texel_size, shadow_maximum_filter_uv);
return pcf_filter(uv, reference, filter_radius);
}
FSOutput main(FSInput input) {
float3 light_direction = normalize(light.direction);
float3 normal = normalize(input.normal);
float3 view_direction = normalize(input.camera_position - input.world_position);
float3 halfway_direction = normalize(light_direction + view_direction);
float normal_dot_light = dot(normal, light_direction);
float diffuse = max(normal_dot_light, 0.0);
float specular = diffuse > 0.0 ? pow(max(dot(normal, halfway_direction), 0.0), shininess) : 0.0;
float visibility = shadow_visibility(input.light_space_position, normal_dot_light);
visibility = lerp(1.0, visibility, light.shadow_strength);
float shade = saturate(ambient_strength + visibility * (diffuse * diffuse_strength + specular * specular_strength));
FSOutput output;
output.out_color = float4(shade, shade, shade, 1.0);
return output;
}
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