//! Material shader — 3D PBR rendering path.
//! Handles modes: 13 (PBR surface), 14 (raymarched reflections), 21 (raymarched cube).
//! Separated from opaque to reduce register pressure from raymarching loops.
@group(3) @binding(4) var t_shadow: texture_depth_2d;
@group(3) @binding(5) var s_shadow: sampler_comparison;
fn sample_shadow(light_vp: mat4x4<f32>, world_pos: vec3<f32>) -> f32 {
let light_pos = light_vp * vec4<f32>(world_pos, 1.0);
let light_uv = light_pos.xy / light_pos.w * 0.5 + 0.5;
let light_depth = light_pos.z / light_pos.w;
// PCF 3x3
let texel_size = 1.0 / scene.shadow_map_size;
var shadow = 0.0;
for (var dx = -1; dx <= 1; dx++) {
for (var dy = -1; dy <= 1; dy++) {
let offset = vec2<f32>(f32(dx), f32(dy)) * texel_size;
shadow += textureSampleCompare(t_shadow, s_shadow,
light_uv + offset, light_depth - scene.shadow_bias);
}
}
return shadow / 9.0;
}
@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
var color = in.color;
if in.material_id == 13u {
// ── Mode 13: 3D Surface — Basic PBR Lighting Model with Shadows
let metallic = in.slice.x;
let roughness = in.slice.y;
let opacity = in.slice.z;
let n = normalize(in.normal);
let light_dir = normalize(scene.light_direction);
let light_color = scene.light_color;
// Shadow mapping
let shadow = sample_shadow(scene.light_vp, in.world_pos);
let n_dot_l = max(dot(n, light_dir), 0.0);
let diffuse = n_dot_l * light_color * shadow;
let view_dir = normalize(scene.camera_pos - in.world_pos);
let half_dir = normalize(light_dir + view_dir);
let n_dot_h = max(dot(n, half_dir), 0.0);
let shininess = mix(8.0, 256.0, 1.0 - roughness);
let spec = pow(n_dot_h, shininess) * light_color * shadow;
let f0 = mix(vec3<f32>(0.04), in.color.rgb, metallic);
let fresnel = f0 + (vec3<f32>(1.0) - f0) * pow(1.0 - max(dot(n, -view_dir), 0.0), 5.0);
let ambient = vec3<f32>(0.06, 0.07, 0.1);
var lit_color = in.color.rgb * (ambient + diffuse);
lit_color += spec * mix(vec3<f32>(1.0), in.color.rgb, metallic) * fresnel;
let depth = in.clip_position.z;
let fog_factor = clamp(1.0 - depth * 0.0005, 0.7, 1.0);
lit_color *= fog_factor;
color = vec4<f32>(lit_color, in.color.a * opacity);
} else if in.material_id == 14u {
// ── Mode 14: Ray Marched Reflections
let ro = vec3<f32>(in.uv.x - 0.5, in.uv.y - 0.5, -2.0);
let rd = normalize(vec3<f32>(in.uv.x - 0.5, in.uv.y - 0.5, 1.0));
let t = ray_march(ro, rd);
if t > 0.0 {
let p = ro + rd * t;
let n = calc_normal(p);
let light_dir = normalize(vec3<f32>(1.0, 1.0, -1.0));
let diff = max(dot(n, light_dir), 0.2);
let ref_rd = reflect(rd, n);
let ref_t = ray_march(p + n * 0.01, ref_rd);
var reflection_color = vec3<f32>(0.05, 0.05, 0.1);
if ref_t > 0.0 { reflection_color = mix(theme.primary_neon.rgb, theme.shatter_neon.rgb, 0.5); }
color = vec4<f32>(mix(in.color.rgb * diff, reflection_color, 0.3), 1.0);
} else { discard; }
} else if in.material_id == 21u {
// ── Mode 21: High-Fidelity Raymarched Cube
let uv_local = (in.uv - 0.5) * 2.0;
let ro = vec3<f32>(0.0, 0.0, -2.5);
let rd = normalize(vec3<f32>(uv_local.x, uv_local.y, 1.5));
let m = rotX(in.slice.x) * rotY(in.slice.y) * rotZ(in.slice.z);
var t = 0.0;
var hit = false;
var d = 0.0;
for (var i = 0; i < 40; i++) {
let p = m * (ro + rd * t);
d = sd_box_3d(p, vec3(0.5, 0.5, 0.5));
if d < 0.001 { hit = true; break; }
t += d;
if t > 5.0 { break; }
}
if hit {
let p = m * (ro + rd * t);
let eps = vec2(0.001, 0.0);
let n = normalize(vec3(
sd_box_3d(p + eps.xyy, vec3(0.5)) - sd_box_3d(p - eps.xyy, vec3(0.5)),
sd_box_3d(p + eps.yxy, vec3(0.5)) - sd_box_3d(p - eps.yxy, vec3(0.5)),
sd_box_3d(p + eps.yyx, vec3(0.5)) - sd_box_3d(p - eps.yyx, vec3(0.5))
));
let light_dir = normalize(vec3(1.0, 1.0, -2.0));
let diff = max(dot(n, light_dir), 0.1);
let rim = pow(1.0 - max(dot(n, -rd), 0.0), 3.0) * 0.5;
color = vec4<f32>(in.color.rgb * diff + rim, in.color.a);
} else {
discard;
}
}
if color.a <= 0.0 { discard; }
return color;
}