93b9a840ff
Keep storage fast paths on capable adapters and use packed or texture fallbacks only when device limits require them.\n\nCompact mesh-edge varyings to avoid WebGL shader rejection.
310 lines
14 KiB
WebGPU Shading Language
310 lines
14 KiB
WebGPU Shading Language
// Wire shader — renders 1-D CAD entities as screen-aligned quads.
|
||
// Topology: TriangleList, 6 vertices drawn per INSTANCE.
|
||
//
|
||
// One instance = one segment. The six vertex IDs map to the corners of a
|
||
// two-triangle quad; the vertex shader derives `which_end` (0=A end, 1=B end)
|
||
// and `side` (±1 perpendicular) from `@builtin(vertex_index)` and expands the
|
||
// quad by `half_width` pixels perpendicular to the segment direction in
|
||
// screen space.
|
||
//
|
||
// Linetype is applied entirely on the GPU:
|
||
// • distance = cumulative arc-length, linearly interpolated from
|
||
// (distance_a, distance_b) by `which_end`.
|
||
// • pattern_length > 0 enables the dash test; 0 = solid (no discard).
|
||
// • pat0/pat1 encode up to 8 elements: positive=dash, negative=gap,
|
||
// exactly 0=dot (rendered as a fixed ~1 px mark). Trailing 0.0 slots are
|
||
// padding; the real element count is (index of last non-zero) + 1.
|
||
|
||
struct Uniforms {
|
||
viewport_size: vec2<f32>,
|
||
world_per_pixel: f32,
|
||
// LWDISPLAY toggle: 0.0 = force 1 px (half_width 0.5), 1.0 = use the
|
||
// per-instance baked half_width. Lets the LWT button switch without
|
||
// retessellating.
|
||
lwdisplay_enable: f32,
|
||
// Mesh flat-shade flag (unused here; kept so the field offsets match
|
||
// the shared Uniforms buffer layout).
|
||
flat_shade: f32,
|
||
// Transparency-display toggle: 1.0 = honour baked alpha, 0.0 = force
|
||
// every line opaque.
|
||
transparency_enable: f32,
|
||
linetype_scale: f32,
|
||
_pad: f32,
|
||
// ── Relative-to-eye (double-single) ──────────────────────────────────
|
||
// view_rot is the rotation-only view-projection; vertices subtract the eye
|
||
// (eye_high + eye_low, two f32 emulating f64) before transforming, so the
|
||
// large eye translation never enters the f32 matrix → no large-coordinate
|
||
// jitter on pan / zoom / rotate.
|
||
view_rot: mat4x4<f32>,
|
||
eye_high: vec3<f32>,
|
||
_pad_eh: f32,
|
||
eye_low: vec3<f32>,
|
||
_pad_el: f32,
|
||
}
|
||
@group(0) @binding(0) var<uniform> u: Uniforms;
|
||
|
||
// Scalars are packed into vec4 attributes: WebGL2 / WebGPU cap vertex
|
||
// attributes at 16, and the unpacked layout had grown to 17 — the wire
|
||
// pipeline failed to build and the web viewport drew no lines at all (#414).
|
||
struct InstanceIn {
|
||
@location(0) pos_a: vec3<f32>,
|
||
@location(1) pos_b: vec3<f32>,
|
||
@location(2) color: vec4<f32>,
|
||
// distance_a, distance_b, half_width, pattern_length
|
||
@location(3) dists: vec4<f32>,
|
||
@location(4) pat0: vec4<f32>,
|
||
@location(5) pat1: vec4<f32>,
|
||
// draw_depth, align_end ("A"-type end-dash length), align_total (total
|
||
// wire length), world_half_width (wide-polyline band; 0 = normal wire)
|
||
@location(6) misc: vec4<f32>,
|
||
// Double-single low residuals of the endpoints.
|
||
@location(7) pos_a_low: vec3<f32>,
|
||
@location(8) pos_b_low: vec3<f32>,
|
||
// Per-endpoint world half-width for a tapered band (0 = use the constant).
|
||
@location(9) taper: vec2<f32>,
|
||
}
|
||
|
||
// Draw-order depth bias: shifts clip-space z so 2D entities of different
|
||
// types order against each other through the shared LessEqual depth test.
|
||
// draw_depth is signed (-1,1): front → positive → smaller z → drawn on top;
|
||
// 0.0 = neutral (real depth). Depth32Float gives ample precision.
|
||
const DRAW_ORDER_BIAS: f32 = 0.001;
|
||
|
||
struct VertexOut {
|
||
@builtin(position) clip_pos: vec4<f32>,
|
||
@location(0) color: vec4<f32>,
|
||
@location(1) distance: f32,
|
||
@location(2) pattern_length: f32,
|
||
@location(3) pat0: vec4<f32>,
|
||
@location(4) pat1: vec4<f32>,
|
||
// World length of the smallest non-zero dash / gap element of this
|
||
// instance. Flat-interpolated (constant per instance) so the
|
||
// fragment stage can short-circuit the dash test when every gap
|
||
// projects below one pixel on screen. See the LOD branch in
|
||
// `fs_main`.
|
||
@location(5) @interpolate(flat) min_elem: f32,
|
||
@location(6) @interpolate(flat) align_end: f32,
|
||
@location(7) @interpolate(flat) align_total: f32,
|
||
// Round-cap support: (along, across) of this fragment in screen pixels,
|
||
// where `along` runs -hw_a … seg_len+hw_b over the extended quad and
|
||
// `across` is the signed distance from the centreline.
|
||
@location(8) cap: vec2<f32>,
|
||
// (segment pixel length, end half-width at A, end half-width at B).
|
||
@location(9) @interpolate(flat) cap_ends: vec3<f32>,
|
||
}
|
||
|
||
// Half-width of one segment end: a tapered band's own end width wins, then a
|
||
// constant world-unit band, then the screen-pixel lineweight (LWDISPLAY off
|
||
// collapses to a hairline).
|
||
fn resolve_hw(taper: f32, world_hw: f32, px_hw: f32) -> f32 {
|
||
if taper > 0.0 { return max(taper / u.world_per_pixel, 0.5); }
|
||
if world_hw > 0.0 { return max(world_hw / u.world_per_pixel, 0.5); }
|
||
return select(0.5, px_hw, u.lwdisplay_enable > 0.5);
|
||
}
|
||
|
||
@vertex fn vs_main(@builtin(vertex_index) vid: u32, in: InstanceIn) -> VertexOut {
|
||
// Two-triangle quad corner table:
|
||
// vid 0,1,2 = (A,-1) (B,-1) (B,+1)
|
||
// vid 3,4,5 = (A,-1) (B,+1) (A,+1)
|
||
let which_end_arr = array<f32, 6>(0.0, 1.0, 1.0, 0.0, 1.0, 0.0);
|
||
let side_arr = array<f32, 6>(-1.0, -1.0, 1.0, -1.0, 1.0, 1.0);
|
||
let which_end = which_end_arr[vid];
|
||
let side = side_arr[vid];
|
||
|
||
// Double-single relative-to-eye: subtract the eye from each endpoint with
|
||
// both halves of the f64-emulating pair, then transform by the rotation-only
|
||
// view-projection. (pos_high − eye_high) is exact in f32 for same-magnitude
|
||
// operands (Sterbenz); adding (pos_low − eye_low) restores the residual both
|
||
// the vertex and the eye would otherwise lose — so geometry stays put at
|
||
// UTM-scale coordinates and after a cross-drawing paste, with no jitter.
|
||
let rel_a = (in.pos_a - u.eye_high) + (in.pos_a_low - u.eye_low);
|
||
let rel_b = (in.pos_b - u.eye_high) + (in.pos_b_low - u.eye_low);
|
||
let clip_a = u.view_rot * vec4<f32>(rel_a, 1.0);
|
||
let clip_b = u.view_rot * vec4<f32>(rel_b, 1.0);
|
||
|
||
// NDC of both endpoints.
|
||
let ndc_a = clip_a.xy / clip_a.w;
|
||
let ndc_b = clip_b.xy / clip_b.w;
|
||
|
||
// Screen-space pixel positions.
|
||
let screen_a = ndc_a * u.viewport_size * 0.5;
|
||
let screen_b = ndc_b * u.viewport_size * 0.5;
|
||
|
||
// Screen-space direction / perpendicular of the segment.
|
||
let seg = screen_b - screen_a;
|
||
let seg_len = length(seg);
|
||
var dir: vec2<f32>;
|
||
if seg_len > 1e-4 {
|
||
dir = seg / seg_len;
|
||
} else {
|
||
dir = vec2<f32>(1.0, 0.0);
|
||
}
|
||
let perp = vec2<f32>(-dir.y, dir.x);
|
||
|
||
// Select the clip-space position for this vertex's endpoint.
|
||
let clip_pos = mix(clip_a, clip_b, which_end);
|
||
|
||
// A wide polyline carries its band width in world units: expand the quad by
|
||
// `world_half_width / world_per_pixel` (pixels) so the band tracks zoom. A
|
||
// normal wire (world_half_width == 0) uses the screen-pixel half-width,
|
||
// honouring the LWDISPLAY toggle (off → collapse to a 1-pixel line).
|
||
// A tapered band interpolates a per-endpoint world half-width across the
|
||
// segment; a constant band uses `world_half_width`. Both clamp to a
|
||
// half-pixel so a zoomed-out band stays a hairline instead of vanishing.
|
||
let hw_a = resolve_hw(in.taper.x, in.misc.w, in.dists.z);
|
||
let hw_b = resolve_hw(in.taper.y, in.misc.w, in.dists.z);
|
||
let hw = mix(hw_a, hw_b, which_end);
|
||
|
||
// Extend the quad longitudinally by the end half-width and let the
|
||
// fragment stage round the overhang off: adjoining segments then meet in
|
||
// overlapping round joints, closing the wedge gaps a perpendicular-only
|
||
// expansion leaves on the outside of corners and along tessellated arcs.
|
||
let ext = which_end * 2.0 - 1.0; // -1 at the A end, +1 at the B end
|
||
let offset_px = perp * hw * side + dir * hw * ext;
|
||
let ndc_offset = offset_px / (u.viewport_size * 0.5);
|
||
let final_clip = clip_pos + vec4<f32>(ndc_offset * clip_pos.w, 0.0, 0.0);
|
||
|
||
// Smallest non-zero dash / gap element, in world units. Used by
|
||
// the fragment stage to decide when the pattern's finest feature
|
||
// would render below one pixel and should collapse to a solid line.
|
||
let lt_scale = u.linetype_scale;
|
||
var min_elem: f32 = in.dists.w * lt_scale;
|
||
let elems = array<f32, 8>(
|
||
in.pat0.x * lt_scale, in.pat0.y * lt_scale,
|
||
in.pat0.z * lt_scale, in.pat0.w * lt_scale,
|
||
in.pat1.x * lt_scale, in.pat1.y * lt_scale,
|
||
in.pat1.z * lt_scale, in.pat1.w * lt_scale,
|
||
);
|
||
for (var i = 0u; i < 8u; i++) {
|
||
let e = abs(elems[i]);
|
||
if e > 0.0 && e < min_elem { min_elem = e; }
|
||
}
|
||
|
||
var out: VertexOut;
|
||
out.clip_pos = final_clip;
|
||
out.clip_pos.z = out.clip_pos.z - in.misc.x * DRAW_ORDER_BIAS * out.clip_pos.w;
|
||
out.color = in.color;
|
||
// Dash arc-length, extrapolated over the cap overhang so the pattern
|
||
// stays continuous through a joint.
|
||
out.distance = mix(in.dists.x, in.dists.y, which_end)
|
||
+ ext * hw * u.world_per_pixel;
|
||
out.cap = vec2<f32>(which_end * seg_len + ext * hw, hw * side);
|
||
out.cap_ends = vec3<f32>(seg_len, hw_a, hw_b);
|
||
out.pattern_length = in.dists.w * lt_scale;
|
||
out.pat0 = in.pat0 * lt_scale;
|
||
out.pat1 = in.pat1 * lt_scale;
|
||
out.min_elem = min_elem;
|
||
out.align_end = in.misc.y * lt_scale;
|
||
out.align_total = in.misc.z;
|
||
return out;
|
||
}
|
||
|
||
// Returns true if arc-length `dist` falls inside a dash or on a dot.
|
||
fn in_dash(dist: f32, pat_len: f32, p0: vec4<f32>, p1: vec4<f32>, align_end: f32, align_total: f32) -> bool {
|
||
let elems = array<f32, 8>(p0.x, p0.y, p0.z, p0.w, p1.x, p1.y, p1.z, p1.w);
|
||
// Real element count = (index of last non-zero) + 1. Trailing 0.0 slots
|
||
// are padding; a 0.0 within this range is a real dot.
|
||
var count = 0u;
|
||
for (var i = 0u; i < 8u; i++) {
|
||
if elems[i] != 0.0 { count = i + 1u; }
|
||
}
|
||
|
||
var d: f32;
|
||
if align_total > 0.0 {
|
||
// "A"-type alignment: the line begins and ends with a solid dash of
|
||
// length `align_end`. Force the two end regions lit, then phase the
|
||
// interior so the element AFTER the first dash resumes exactly at
|
||
// `align_end` (the interior meets each end dash on a gap boundary).
|
||
if dist <= align_end || dist >= align_total - align_end {
|
||
return true;
|
||
}
|
||
var first_dash = 0.0;
|
||
for (var i = 0u; i < count; i++) {
|
||
if elems[i] > 0.0 { first_dash = elems[i]; break; }
|
||
}
|
||
d = ((dist - align_end + first_dash) % pat_len + pat_len) % pat_len;
|
||
} else {
|
||
d = ((dist % pat_len) + pat_len) % pat_len;
|
||
}
|
||
|
||
var pos = 0.0f;
|
||
// A dot is a zero-length element: render it as a fixed ~1.5 px mark
|
||
// (half-width ~0.75 px in world units) so it stays visible at any zoom
|
||
// instead of vanishing with its zero world-length. Mirrors the hatch
|
||
// shader's pixel-snapped dot. (#149)
|
||
let dot_half = u.world_per_pixel * 0.75;
|
||
for (var i = 0u; i < count; i++) {
|
||
let elem = elems[i];
|
||
if elem == 0.0 {
|
||
// Dot centred at `pos` (zero length); light a small mark, wrapped
|
||
// around the pattern so a dot at 0 also covers the seam at pat_len.
|
||
let dd = abs(d - pos);
|
||
if min(dd, pat_len - dd) <= dot_half { return true; }
|
||
} else if elem > 0.0 {
|
||
if d >= pos && d < pos + elem { return true; } // inside a dash
|
||
pos += elem;
|
||
} else {
|
||
pos += -elem; // skip a gap
|
||
}
|
||
}
|
||
return false;
|
||
}
|
||
|
||
// Round the cap overhang off: outside the segment span only pixels within
|
||
// the end's half-width radius survive, giving round joints and end caps.
|
||
fn cap_clipped(cap: vec2<f32>, cap_ends: vec3<f32>) -> bool {
|
||
if cap.x < 0.0 {
|
||
return length(cap) > cap_ends.y;
|
||
}
|
||
if cap.x > cap_ends.x {
|
||
return length(vec2<f32>(cap.x - cap_ends.x, cap.y)) > cap_ends.z;
|
||
}
|
||
return false;
|
||
}
|
||
|
||
@fragment fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
|
||
// Negative pattern length is the persistent-arena tombstone sentinel.
|
||
// Discard before cap/alpha work so deleted slabs cannot write color/depth.
|
||
if in.pattern_length < 0.0 {
|
||
discard;
|
||
}
|
||
if cap_clipped(in.cap, in.cap_ends) {
|
||
discard;
|
||
}
|
||
if in.pattern_length > 0.0 {
|
||
// LOD: once the pattern's smallest feature drops below ~1 px
|
||
// on screen, dash gaps alias / shimmer (or vanish completely)
|
||
// and the user reads the line as solid anyway. Skip the dash
|
||
// test and return solid colour — also saves the per-fragment
|
||
// arc-length math + `discard`.
|
||
if in.min_elem >= u.world_per_pixel {
|
||
if !in_dash(in.distance, in.pattern_length, in.pat0, in.pat1, in.align_end, in.align_total) {
|
||
discard;
|
||
}
|
||
}
|
||
}
|
||
// Transparency display off → force the line opaque.
|
||
let alpha = select(1.0, in.color.a, u.transparency_enable > 0.5);
|
||
return vec4<f32>(in.color.rgb, alpha);
|
||
}
|
||
|
||
// Black variant: used for 3D mesh outline edges in filled render modes so the
|
||
// mesh reads as a shaded surface framed by black edges. Keeps the dash/LOD
|
||
// logic identical to `fs_main`; only the RGB is forced to black.
|
||
@fragment fn fs_black(in: VertexOut) -> @location(0) vec4<f32> {
|
||
if in.pattern_length < 0.0 {
|
||
discard;
|
||
}
|
||
if cap_clipped(in.cap, in.cap_ends) {
|
||
discard;
|
||
}
|
||
if in.pattern_length > 0.0 {
|
||
if in.min_elem >= u.world_per_pixel {
|
||
if !in_dash(in.distance, in.pattern_length, in.pat0, in.pat1, in.align_end, in.align_total) {
|
||
discard;
|
||
}
|
||
}
|
||
}
|
||
let alpha = select(1.0, in.color.a, u.transparency_enable > 0.5);
|
||
return vec4<f32>(0.0, 0.0, 0.0, alpha);
|
||
}
|