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// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
// Finish prefix sum of drawtags, decode draw objects.
#import config
#import clip
#import drawtag
#import bbox
#import transform
@group(0) @binding(0)
var<uniform> config: Config;
@group(0) @binding(1)
var<storage> scene: array<u32>;
@group(0) @binding(2)
var<storage> reduced: array<DrawMonoid>;
@group(0) @binding(3)
var<storage> path_bbox: array<PathBbox>;
@group(0) @binding(4)
var<storage, read_write> draw_monoid: array<DrawMonoid>;
@group(0) @binding(5)
var<storage, read_write> info: array<u32>;
@group(0) @binding(6)
var<storage, read_write> clip_inp: array<ClipInp>;
#import util
let WG_SIZE = 256u;
fn read_transform(transform_base: u32, ix: u32) -> Transform {
let base = transform_base + ix * 6u;
let c0 = bitcast<f32>(scene[base]);
let c1 = bitcast<f32>(scene[base + 1u]);
let c2 = bitcast<f32>(scene[base + 2u]);
let c3 = bitcast<f32>(scene[base + 3u]);
let c4 = bitcast<f32>(scene[base + 4u]);
let c5 = bitcast<f32>(scene[base + 5u]);
let matrx = vec4(c0, c1, c2, c3);
let translate = vec2(c4, c5);
return Transform(matrx, translate);
}
var<workgroup> sh_scratch: array<DrawMonoid, WG_SIZE>;
@compute @workgroup_size(256)
fn main(
@builtin(global_invocation_id) global_id: vec3<u32>,
@builtin(local_invocation_id) local_id: vec3<u32>,
@builtin(workgroup_id) wg_id: vec3<u32>,
) {
let ix = global_id.x;
// Reduce prefix of workgroups up to this one
var agg = draw_monoid_identity();
if local_id.x < wg_id.x {
agg = reduced[local_id.x];
}
sh_scratch[local_id.x] = agg;
for (var i = 0u; i < firstTrailingBit(WG_SIZE); i += 1u) {
workgroupBarrier();
if local_id.x + (1u << i) < WG_SIZE {
let other = sh_scratch[local_id.x + (1u << i)];
agg = combine_draw_monoid(agg, other);
}
workgroupBarrier();
sh_scratch[local_id.x] = agg;
}
// Two barriers can be eliminated if we use separate shared arrays
// for prefix and intra-workgroup prefix sum.
workgroupBarrier();
var m = sh_scratch[0];
workgroupBarrier();
let tag_word = read_draw_tag_from_scene(ix);
agg = map_draw_tag(tag_word);
sh_scratch[local_id.x] = agg;
for (var i = 0u; i < firstTrailingBit(WG_SIZE); i += 1u) {
workgroupBarrier();
if local_id.x >= 1u << i {
let other = sh_scratch[local_id.x - (1u << i)];
agg = combine_draw_monoid(agg, other);
}
workgroupBarrier();
sh_scratch[local_id.x] = agg;
}
workgroupBarrier();
if local_id.x > 0u {
m = combine_draw_monoid(m, sh_scratch[local_id.x - 1u]);
}
// m now contains exclusive prefix sum of draw monoid
if ix < config.n_drawobj {
draw_monoid[ix] = m;
}
let dd = config.drawdata_base + m.scene_offset;
let di = m.info_offset;
if tag_word == DRAWTAG_FILL_COLOR || tag_word == DRAWTAG_FILL_LIN_GRADIENT ||
tag_word == DRAWTAG_FILL_RAD_GRADIENT || tag_word == DRAWTAG_FILL_IMAGE ||
tag_word == DRAWTAG_BEGIN_CLIP
{
let bbox = path_bbox[m.path_ix];
// TODO: bbox is mostly yagni here, sort that out. Maybe clips?
// let x0 = f32(bbox.x0);
// let y0 = f32(bbox.y0);
// let x1 = f32(bbox.x1);
// let y1 = f32(bbox.y1);
// let bbox_f = vec4(x0, y0, x1, y1);
let fill_mode = u32(bbox.linewidth >= 0.0);
var transform = Transform();
var linewidth = bbox.linewidth;
if linewidth >= 0.0 || tag_word == DRAWTAG_FILL_LIN_GRADIENT || tag_word == DRAWTAG_FILL_RAD_GRADIENT ||
tag_word == DRAWTAG_FILL_IMAGE
{
transform = read_transform(config.transform_base, bbox.trans_ix);
}
if linewidth >= 0.0 {
// Note: doesn't deal with anisotropic case
let matrx = transform.matrx;
linewidth *= sqrt(abs(matrx.x * matrx.w - matrx.y * matrx.z));
}
switch tag_word {
// DRAWTAG_FILL_COLOR
case 0x44u: {
info[di] = bitcast<u32>(linewidth);
}
// DRAWTAG_FILL_LIN_GRADIENT
case 0x114u: {
info[di] = bitcast<u32>(linewidth);
var p0 = bitcast<vec2<f32>>(vec2(scene[dd + 1u], scene[dd + 2u]));
var p1 = bitcast<vec2<f32>>(vec2(scene[dd + 3u], scene[dd + 4u]));
p0 = transform_apply(transform, p0);
p1 = transform_apply(transform, p1);
let dxy = p1 - p0;
let scale = 1.0 / dot(dxy, dxy);
let line_xy = dxy * scale;
let line_c = -dot(p0, line_xy);
info[di + 1u] = bitcast<u32>(line_xy.x);
info[di + 2u] = bitcast<u32>(line_xy.y);
info[di + 3u] = bitcast<u32>(line_c);
}
// DRAWTAG_FILL_RAD_GRADIENT
case 0x29cu: {
// Two-point conical gradient implementation based
// on the algorithm at <https://skia.org/docs/dev/design/conical/>
// This epsilon matches what Skia uses
let GRADIENT_EPSILON = 1.0 / f32(1 << 12u);
info[di] = bitcast<u32>(linewidth);
var p0 = bitcast<vec2<f32>>(vec2(scene[dd + 1u], scene[dd + 2u]));
var p1 = bitcast<vec2<f32>>(vec2(scene[dd + 3u], scene[dd + 4u]));
var r0 = bitcast<f32>(scene[dd + 5u]);
var r1 = bitcast<f32>(scene[dd + 6u]);
let user_to_gradient = transform_inverse(transform);
// Output variables
var xform = Transform();
var focal_x = 0.0;
var radius = 0.0;
var kind = 0u;
var flags = 0u;
if abs(r0 - r1) <= GRADIENT_EPSILON {
// When the radii are the same, emit a strip gradient
kind = RAD_GRAD_KIND_STRIP;
let scaled = r0 / distance(p0, p1);
xform = transform_mul(
two_point_to_unit_line(p0, p1),
user_to_gradient
);
radius = scaled * scaled;
} else {
// Assume a two point conical gradient unless the centers
// are equal.
kind = RAD_GRAD_KIND_CONE;
if all(p0 == p1) {
kind = RAD_GRAD_KIND_CIRCULAR;
// Nudge p0 a bit to avoid denormals.
p0 += GRADIENT_EPSILON;
}
if r1 == 0.0 {
// If r1 == 0.0, swap the points and radii
flags |= RAD_GRAD_SWAPPED;
let tmp_p = p0;
p0 = p1;
p1 = tmp_p;
let tmp_r = r0;
r0 = r1;
r1 = tmp_r;
}
focal_x = r0 / (r0 - r1);
let cf = (1.0 - focal_x) * p0 + focal_x * p1;
radius = r1 / (distance(cf, p1));
let user_to_unit_line = transform_mul(
two_point_to_unit_line(cf, p1),
user_to_gradient
);
var user_to_scaled = user_to_unit_line;
// When r == 1.0, focal point is on circle
if abs(radius - 1.0) <= GRADIENT_EPSILON {
kind = RAD_GRAD_KIND_FOCAL_ON_CIRCLE;
let scale = 0.5 * abs(1.0 - focal_x);
user_to_scaled = transform_mul(
Transform(vec4(scale, 0.0, 0.0, scale), vec2(0.0)),
user_to_unit_line
);
} else {
let a = radius * radius - 1.0;
let scale_ratio = abs(1.0 - focal_x) / a;
let scale_x = radius * scale_ratio;
let scale_y = sqrt(abs(a)) * scale_ratio;
user_to_scaled = transform_mul(
Transform(vec4(scale_x, 0.0, 0.0, scale_y), vec2(0.0)),
user_to_unit_line
);
}
xform = user_to_scaled;
}
info[di + 1u] = bitcast<u32>(xform.matrx.x);
info[di + 2u] = bitcast<u32>(xform.matrx.y);
info[di + 3u] = bitcast<u32>(xform.matrx.z);
info[di + 4u] = bitcast<u32>(xform.matrx.w);
info[di + 5u] = bitcast<u32>(xform.translate.x);
info[di + 6u] = bitcast<u32>(xform.translate.y);
info[di + 7u] = bitcast<u32>(focal_x);
info[di + 8u] = bitcast<u32>(radius);
info[di + 9u] = bitcast<u32>((flags << 3u) | kind);
}
// DRAWTAG_FILL_IMAGE
case 0x248u: {
info[di] = bitcast<u32>(linewidth);
let inv = transform_inverse(transform);
info[di + 1u] = bitcast<u32>(inv.matrx.x);
info[di + 2u] = bitcast<u32>(inv.matrx.y);
info[di + 3u] = bitcast<u32>(inv.matrx.z);
info[di + 4u] = bitcast<u32>(inv.matrx.w);
info[di + 5u] = bitcast<u32>(inv.translate.x);
info[di + 6u] = bitcast<u32>(inv.translate.y);
info[di + 7u] = scene[dd];
info[di + 8u] = scene[dd + 1u];
}
default: {}
}
}
if tag_word == DRAWTAG_BEGIN_CLIP || tag_word == DRAWTAG_END_CLIP {
var path_ix = ~ix;
if tag_word == DRAWTAG_BEGIN_CLIP {
path_ix = m.path_ix;
}
clip_inp[m.clip_ix] = ClipInp(ix, i32(path_ix));
}
}
fn two_point_to_unit_line(p0: vec2<f32>, p1: vec2<f32>) -> Transform {
let tmp1 = from_poly2(p0, p1);
let inv = transform_inverse(tmp1);
let tmp2 = from_poly2(vec2(0.0), vec2(1.0, 0.0));
return transform_mul(tmp2, inv);
}
fn from_poly2(p0: vec2<f32>, p1: vec2<f32>) -> Transform {
return Transform(
vec4(p1.y - p0.y, p0.x - p1.x, p1.x - p0.x, p1.y - p0.y),
vec2(p0.x, p0.y)
);
}