// OIT (order-independent transparency) mesh shader — McGuire & Bavoil weighted blended.
//
// Identical to mesh.wgsl except for the fragment output: instead of writing a
// single RGBA color to the HDR target, this shader writes to two targets:
// @location(0) accum — Rgba16Float accumulation buffer
// @location(1) reveal — R8Unorm reveal (transmittance) buffer
//
// The weighted-blended OIT formula is applied after computing the fully-lit
// color (same Blinn-Phong / Cook-Torrance path as mesh.wgsl).
//
// Group 0: Camera uniform, shadow atlas, lights, clip planes, shadow info (unchanged).
// Group 1: Object uniform, albedo texture, sampler, normal map, AO map, LUT, scalar buffer.
struct Camera {
view_proj: mat4x4<f32>,
eye_pos: vec3<f32>,
_pad: f32,
};
struct SingleLight {
light_view_proj: mat4x4<f32>,
pos_or_dir: vec3<f32>,
light_type: u32,
color: vec3<f32>,
intensity: f32,
range: f32,
inner_angle: f32,
outer_angle: f32,
spot_direction: vec3<f32>,
_pad: vec2<f32>,
};
struct Lights {
count: u32,
shadow_bias: f32,
shadows_enabled: u32,
_pad: u32,
sky_color: vec3<f32>,
hemisphere_intensity: f32,
ground_color: vec3<f32>,
_pad2: f32,
lights: array<SingleLight, 8>,
};
struct ClipPlanes {
planes: array<vec4<f32>, 6>,
count: u32,
_pad0: u32,
viewport_width: f32,
viewport_height: f32,
};
struct ShadowAtlas {
cascade_vp: array<mat4x4<f32>, 4>,
cascade_splits: vec4<f32>,
cascade_count: u32,
atlas_size: f32,
shadow_filter: u32,
pcss_light_radius: f32,
atlas_rects: array<vec4<f32>, 8>,
};
struct Object {
model: mat4x4<f32>,
color: vec4<f32>,
selected: u32,
wireframe: u32,
ambient: f32,
diffuse: f32,
specular: f32,
shininess: f32,
has_texture: u32,
use_pbr: u32,
metallic: f32,
roughness: f32,
has_normal_map: u32,
has_ao_map: u32,
has_attribute: u32,
scalar_min: f32,
scalar_max: f32,
_pad_scalar: u32,
nan_color: vec4<f32>, // offset 144
use_nan_color: u32, // offset 160
_pad_nan0: u32,
_pad_nan1: u32,
_pad_nan2: u32,
};
struct ClipVolumeUB {
volume_type: u32,
_pad0: u32, _pad1: u32, _pad2: u32,
plane_normal: vec3<f32>,
plane_dist: f32,
box_center: vec3<f32>,
_padB0: f32,
box_half_extents: vec3<f32>,
_padB1: f32,
box_col0: vec3<f32>,
_padB2: f32,
box_col1: vec3<f32>,
_padB3: f32,
box_col2: vec3<f32>,
_padB4: f32,
sphere_center: vec3<f32>,
sphere_radius: f32,
};
@group(0) @binding(0) var<uniform> camera: Camera;
@group(0) @binding(1) var shadow_map: texture_depth_2d;
@group(0) @binding(2) var shadow_sampler: sampler_comparison;
@group(0) @binding(3) var<uniform> lights_uniform: Lights;
@group(0) @binding(4) var<uniform> clip_planes: ClipPlanes;
@group(0) @binding(5) var<uniform> shadow_atlas: ShadowAtlas;
@group(0) @binding(6) var<uniform> clip_volume: ClipVolumeUB;
fn clip_volume_test(p: vec3<f32>) -> bool {
if clip_volume.volume_type == 0u { return true; }
if clip_volume.volume_type == 1u {
return dot(p, clip_volume.plane_normal) + clip_volume.plane_dist >= 0.0;
}
if clip_volume.volume_type == 2u {
let d = p - clip_volume.box_center;
let local = vec3<f32>(
dot(d, clip_volume.box_col0),
dot(d, clip_volume.box_col1),
dot(d, clip_volume.box_col2),
);
return abs(local.x) <= clip_volume.box_half_extents.x
&& abs(local.y) <= clip_volume.box_half_extents.y
&& abs(local.z) <= clip_volume.box_half_extents.z;
}
let ds = p - clip_volume.sphere_center;
return dot(ds, ds) <= clip_volume.sphere_radius * clip_volume.sphere_radius;
}
@group(1) @binding(0) var<uniform> object: Object;
@group(1) @binding(1) var obj_texture: texture_2d<f32>;
@group(1) @binding(2) var obj_sampler: sampler;
@group(1) @binding(3) var normal_map: texture_2d<f32>;
@group(1) @binding(4) var ao_map: texture_2d<f32>;
@group(1) @binding(5) var lut_texture: texture_2d<f32>;
@group(1) @binding(6) var<storage, read> scalar_buffer: array<f32>;
struct VertexIn {
@location(0) position: vec3<f32>,
@location(1) normal: vec3<f32>,
@location(2) color: vec4<f32>,
@location(3) uv: vec2<f32>,
@location(4) tangent: vec4<f32>,
@builtin(vertex_index) vertex_index: u32,
};
struct VertexOut {
@builtin(position) clip_pos: vec4<f32>,
@location(0) color: vec4<f32>,
@location(1) world_normal: vec3<f32>,
@location(2) world_pos: vec3<f32>,
@location(3) uv: vec2<f32>,
@location(4) world_tangent: vec4<f32>,
@location(5) scalar_val: f32,
@location(6) is_nan_scalar: f32,
};
struct OitOut {
@location(0) accum: vec4<f32>,
@location(1) reveal: f32,
};
@vertex
fn vs_main(in: VertexIn) -> VertexOut {
var out: VertexOut;
let world_pos = object.model * vec4<f32>(in.position, 1.0);
out.clip_pos = camera.view_proj * world_pos;
out.color = in.color;
out.world_pos = world_pos.xyz;
let model3 = mat3x3<f32>(
object.model[0].xyz,
object.model[1].xyz,
object.model[2].xyz,
);
out.world_normal = normalize(model3 * in.normal);
out.world_tangent = vec4<f32>(normalize(model3 * in.tangent.xyz), in.tangent.w);
out.uv = in.uv;
let buf_len = arrayLength(&scalar_buffer);
let idx = in.vertex_index;
let has_attr = object.has_attribute != 0u && buf_len > 0u;
let safe_idx = min(idx, select(0u, buf_len - 1u, buf_len > 0u));
let raw_scalar = scalar_buffer[safe_idx];
out.scalar_val = select(0.0, raw_scalar, has_attr);
let sv_bits = bitcast<u32>(raw_scalar);
let sv_is_nan = has_attr && (sv_bits & 0x7F800000u) == 0x7F800000u && (sv_bits & 0x007FFFFFu) != 0u;
out.is_nan_scalar = select(0.0, 1.0, sv_is_nan);
return out;
}
// ---------------------------------------------------------------------------
// 32-sample Poisson disk (shadow sampling — identical to mesh.wgsl)
// ---------------------------------------------------------------------------
const POISSON_DISK: array<vec2<f32>, 32> = array<vec2<f32>, 32>(
vec2<f32>(-0.94201624, -0.39906216), vec2<f32>( 0.94558609, -0.76890725),
vec2<f32>(-0.09418410, -0.92938870), vec2<f32>( 0.34495938, 0.29387760),
vec2<f32>(-0.91588581, 0.45771432), vec2<f32>(-0.81544232, -0.87912464),
vec2<f32>(-0.38277543, 0.27676845), vec2<f32>( 0.97484398, 0.75648379),
vec2<f32>( 0.44323325, -0.97511554), vec2<f32>( 0.53742981, -0.47373420),
vec2<f32>(-0.26496911, -0.41893023), vec2<f32>( 0.79197514, 0.19090188),
vec2<f32>(-0.24188840, 0.99706507), vec2<f32>(-0.81409955, 0.91437590),
vec2<f32>( 0.19984126, 0.78641367), vec2<f32>( 0.14383161, -0.14100790),
vec2<f32>(-0.44451570, 0.67055830), vec2<f32>( 0.70509040, -0.15854630),
vec2<f32>( 0.07130650, -0.64599580), vec2<f32>( 0.39881030, 0.55789810),
vec2<f32>(-0.60554040, -0.34964830), vec2<f32>( 0.85095100, 0.47178830),
vec2<f32>(-0.47994860, 0.08443340), vec2<f32>(-0.12494190, -0.76098760),
vec2<f32>( 0.64839320, 0.74738240), vec2<f32>(-0.96815740, -0.12345680),
vec2<f32>( 0.27682050, -0.80927180), vec2<f32>(-0.73016460, 0.18344200),
vec2<f32>( 0.54754660, 0.06234570), vec2<f32>(-0.30967360, -0.61021430),
vec2<f32>(-0.57774330, 0.80459740), vec2<f32>( 0.18238670, -0.37596540),
);
fn sample_shadow_csm(world_pos: vec3<f32>, eye_pos: vec3<f32>, surface_normal: vec3<f32>) -> f32 {
let dist = distance(eye_pos, world_pos);
var cascade_idx = 0u;
for (var i = 0u; i < shadow_atlas.cascade_count; i++) {
if dist > shadow_atlas.cascade_splits[i] {
cascade_idx = i + 1u;
}
}
cascade_idx = min(cascade_idx, shadow_atlas.cascade_count - 1u);
let light_clip = shadow_atlas.cascade_vp[cascade_idx] * vec4<f32>(world_pos, 1.0);
let ndc = light_clip.xyz / light_clip.w;
let tile_uv = vec2<f32>(ndc.x * 0.5 + 0.5, -ndc.y * 0.5 + 0.5);
if tile_uv.x < 0.0 || tile_uv.x > 1.0 || tile_uv.y < 0.0 || tile_uv.y > 1.0 ||
ndc.z < 0.0 || ndc.z > 1.0 {
return 1.0;
}
let rect = shadow_atlas.atlas_rects[cascade_idx];
let atlas_uv = vec2<f32>(
mix(rect.x, rect.z, tile_uv.x),
mix(rect.y, rect.w, tile_uv.y),
);
let texel_size = 1.0 / shadow_atlas.atlas_size;
let offset_clip = shadow_atlas.cascade_vp[cascade_idx] * vec4<f32>(world_pos + surface_normal * 0.002, 1.0);
let biased_depth = (offset_clip.xyz / offset_clip.w).z - lights_uniform.shadow_bias;
let noise = fract(52.9829189 * fract(dot(world_pos.xz, vec2<f32>(0.06711056, 0.00583715))));
let rot = noise * 6.28318530;
let sin_r = sin(rot);
let cos_r = cos(rot);
if shadow_atlas.shadow_filter == 1u {
let search_radius = shadow_atlas.pcss_light_radius * 16.0 * texel_size;
var blocker_sum = 0.0;
var blocker_count = 0.0;
for (var i = 0u; i < 16u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * search_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
let sample_depth = textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
if sample_depth < 1.0 {
let coords = vec2<i32>(clamped_uv * shadow_atlas.atlas_size);
let raw_depth = textureLoad(shadow_map, coords, 0);
blocker_sum += raw_depth;
blocker_count += 1.0;
}
}
if blocker_count < 1.0 { return 1.0; }
let avg_blocker = blocker_sum / blocker_count;
let penumbra_width = shadow_atlas.pcss_light_radius * (biased_depth - avg_blocker) / max(avg_blocker, 0.001);
let filter_radius = max(penumbra_width * 16.0 * texel_size, texel_size);
var shadow = 0.0;
for (var i = 0u; i < 32u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * filter_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
shadow += textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
}
return shadow / 32.0;
} else {
let pcf_radius = 4.0 * texel_size;
var shadow = 0.0;
for (var i = 0u; i < 32u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * pcf_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
shadow += textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
}
return shadow / 32.0;
}
}
// ---------------------------------------------------------------------------
// PBR BRDF helpers (Cook-Torrance) — identical to mesh.wgsl
// ---------------------------------------------------------------------------
fn D_GGX(NdotH: f32, roughness: f32) -> f32 {
let a = roughness * roughness;
let a2 = a * a;
let denom = NdotH * NdotH * (a2 - 1.0) + 1.0;
return a2 / (3.14159265 * denom * denom);
}
fn G1_Smith(NdotV: f32, roughness: f32) -> f32 {
let r = roughness + 1.0;
let k = (r * r) / 8.0;
return NdotV / (NdotV * (1.0 - k) + k);
}
fn G_Smith(NdotV: f32, NdotL: f32, roughness: f32) -> f32 {
return G1_Smith(NdotV, roughness) * G1_Smith(NdotL, roughness);
}
fn F_Schlick(cos_theta: f32, F0: vec3<f32>) -> vec3<f32> {
return F0 + (vec3<f32>(1.0) - F0) * pow(clamp(1.0 - cos_theta, 0.0, 1.0), 5.0);
}
fn pbr_light_contrib(
N: vec3<f32>, V: vec3<f32>, L: vec3<f32>, radiance: vec3<f32>,
base_color: vec3<f32>, metallic: f32, roughness: f32, F0: vec3<f32>,
) -> vec3<f32> {
let H = normalize(L + V);
let NdotL = max(dot(N, L), 0.0);
if NdotL <= 0.0 { return vec3<f32>(0.0); }
let NdotV = max(dot(N, V), 0.001);
let NdotH = max(dot(N, H), 0.0);
let HdotV = max(dot(H, V), 0.0);
let D = D_GGX(NdotH, roughness);
let G = G_Smith(NdotV, NdotL, roughness);
let F = F_Schlick(HdotV, F0);
let kS = F;
let kD = (vec3<f32>(1.0) - kS) * (1.0 - metallic);
let specular = (D * G * F) / (4.0 * NdotV * NdotL + 0.001);
return (kD * base_color / 3.14159265 + specular) * radiance * NdotL;
}
// ---------------------------------------------------------------------------
// OIT fragment shader — writes to accum + reveal targets.
// ---------------------------------------------------------------------------
@fragment
fn fs_oit_main(in: VertexOut) -> OitOut {
// Section view clipping.
for (var i = 0u; i < clip_planes.count; i++) {
let plane = clip_planes.planes[i];
if dot(in.world_pos, plane.xyz) + plane.w < 0.0 {
discard;
}
}
if !clip_volume_test(in.world_pos) { discard; }
// Sample texture if one is assigned.
var tex_color = vec4<f32>(1.0);
if object.has_texture == 1u {
tex_color = textureSample(obj_texture, obj_sampler, in.uv);
}
let obj_color = vec4<f32>(
object.color.rgb * in.color.rgb * tex_color.rgb,
object.color.a * in.color.a * tex_color.a,
);
var base_color = obj_color.rgb;
// Scalar attribute colour override.
if object.has_attribute != 0u {
if in.is_nan_scalar > 0.5 {
if object.use_nan_color == 0u {
discard;
}
let alpha = object.nan_color.a;
let z = in.clip_pos.z;
let w = alpha * max(1e-2, min(3e3, 10.0 / (1e-5 + pow(z / 5.0, 2.0) + pow(z / 200.0, 6.0))));
var nan_out: OitOut;
nan_out.accum = vec4<f32>(object.nan_color.rgb * alpha * w, alpha * w);
nan_out.reveal = alpha;
return nan_out;
}
let raw = in.scalar_val;
let range = object.scalar_max - object.scalar_min;
let t = clamp(
select(0.0, (raw - object.scalar_min) / range, range > 0.0001),
0.0, 1.0,
);
base_color = textureSampleLevel(lut_texture, obj_sampler, vec2<f32>(t, 0.5), 0.0).rgb;
}
// Shading normal.
var N: vec3<f32>;
if object.has_normal_map != 0u {
let nm_sample = textureSample(normal_map, obj_sampler, in.uv).rgb;
let ts_normal = normalize(nm_sample * 2.0 - vec3<f32>(1.0));
let T = normalize(in.world_tangent.xyz);
let Ng = normalize(in.world_normal);
let T_orth = normalize(T - dot(T, Ng) * Ng);
let B = cross(Ng, T_orth) * in.world_tangent.w;
let TBN = mat3x3<f32>(T_orth, B, Ng);
N = normalize(TBN * ts_normal);
} else {
N = normalize(in.world_normal);
}
var ao_factor = 1.0;
if object.has_ao_map != 0u {
ao_factor = textureSample(ao_map, obj_sampler, in.uv).r;
}
let V = normalize(camera.eye_pos - in.world_pos);
let tint = vec4<f32>(1.0);
var final_rgb: vec3<f32>;
if object.use_pbr != 0u {
let metallic = clamp(object.metallic, 0.0, 1.0);
let roughness = max(object.roughness, 0.04);
let F0 = mix(vec3<f32>(0.04), base_color, metallic);
var Lo = vec3<f32>(0.0);
for (var i = 0u; i < lights_uniform.count; i++) {
let l = lights_uniform.lights[i];
var L: vec3<f32>;
var radiance: vec3<f32>;
if l.light_type == 0u {
L = normalize(l.pos_or_dir);
radiance = l.color * l.intensity;
} else if l.light_type == 1u {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
L = to_light / max(dist, 0.0001);
let falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
radiance = l.color * l.intensity * falloff * falloff;
} else {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
L = to_light / max(dist, 0.0001);
let dist_falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
let spot_dir = normalize(l.spot_direction);
let cos_angle = dot(-L, spot_dir);
let cos_outer = cos(l.outer_angle);
let cos_inner = cos(l.inner_angle);
let cone_att = clamp(
(cos_angle - cos_outer) / max(cos_inner - cos_outer, 0.0001),
0.0, 1.0,
);
radiance = l.color * l.intensity * dist_falloff * dist_falloff * cone_att;
}
// Transparent surfaces do not cast/receive shadows (no CSM sampling).
Lo += pbr_light_contrib(N, V, L, radiance, base_color, metallic, roughness, F0);
}
let hemi_t = clamp(in.world_normal.y * 0.5 + 0.5, 0.0, 1.0);
let hemi_color = mix(lights_uniform.ground_color, lights_uniform.sky_color, hemi_t);
let ambient_scale = vec3<f32>(object.ambient) + hemi_color * lights_uniform.hemisphere_intensity;
let ambient = ambient_scale * (base_color * (1.0 - metallic) + F0 * metallic) * ao_factor;
final_rgb = clamp((Lo + ambient) * tint.rgb, vec3<f32>(0.0), vec3<f32>(1.0));
} else {
var total_color_contrib = vec3<f32>(0.0);
for (var i = 0u; i < lights_uniform.count; i++) {
let l = lights_uniform.lights[i];
var light_dir: vec3<f32>;
var attenuation = 1.0;
if l.light_type == 0u {
light_dir = normalize(l.pos_or_dir);
} else if l.light_type == 1u {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
light_dir = to_light / max(dist, 0.0001);
let falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
attenuation = falloff * falloff;
} else {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
light_dir = to_light / max(dist, 0.0001);
let dist_falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
let spot_dir = normalize(l.spot_direction);
let cos_angle = dot(-light_dir, spot_dir);
let cos_outer = cos(l.outer_angle);
let cos_inner = cos(l.inner_angle);
let cone_att = clamp(
(cos_angle - cos_outer) / max(cos_inner - cos_outer, 0.0001),
0.0, 1.0,
);
attenuation = dist_falloff * dist_falloff * cone_att;
}
// Transparent surfaces do not participate in shadow evaluation.
let H = normalize(light_dir + V);
let n_dot_l = max(dot(N, light_dir), 0.0);
let n_dot_h = max(dot(N, H), 0.0);
let diffuse_contrib = object.diffuse * n_dot_l * l.intensity * attenuation;
let specular_contrib = object.specular * pow(n_dot_h, object.shininess)
* l.intensity * attenuation;
total_color_contrib += (diffuse_contrib + specular_contrib) * l.color;
}
let ambient_contrib = object.ambient;
let hemi_t = clamp(in.world_normal.y * 0.5 + 0.5, 0.0, 1.0);
let hemi_color = mix(lights_uniform.ground_color, lights_uniform.sky_color, hemi_t);
let hemi_ambient = hemi_color * lights_uniform.hemisphere_intensity;
let lit_rgb = base_color * (ambient_contrib + hemi_ambient) * ao_factor
+ base_color * total_color_contrib;
final_rgb = clamp(lit_rgb * tint.rgb, vec3<f32>(0.0), vec3<f32>(1.0));
}
// ---------------------------------------------------------------------------
// McGuire & Bavoil weighted blended OIT output.
// ---------------------------------------------------------------------------
let alpha = obj_color.a;
let z = in.clip_pos.z; // NDC depth 0..1
let w = alpha * max(1e-2, min(3e3, 10.0 / (1e-5 + pow(z / 5.0, 2.0) + pow(z / 200.0, 6.0))));
var out: OitOut;
out.accum = vec4<f32>(final_rgb * alpha * w, alpha * w);
out.reveal = alpha;
return out;
}