Quelle cs_clip_rectangle.glsl
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include shared,clip_shared,ellipse
varying highp vec4 vLocalPos;
#ifdef WR_FEATURE_FAST_PATH
flat varying highp vec4 v_clip_radii;
flat varying highp vec2 v_clip_size;
#else
flat varying highp vec4 vClipCenter_Radius_TL;
flat varying highp vec4 vClipCenter_Radius_TR;
flat varying highp vec4 vClipCenter_Radius_BL;
flat varying highp vec4 vClipCenter_Radius_BR;
flat varying highp vec3 vClipPlane_TL;
flat varying highp vec3 vClipPlane_TR;
flat varying highp vec3 vClipPlane_BL;
flat varying highp vec3 vClipPlane_BR;
#endif
// Clip mode. Packed in to a vector to work around bug 1630356.
flat varying mediump vec2 vClipMode;
#ifdef WR_VERTEX_SHADER
PER_INSTANCE in vec2 aClipLocalPos;
PER_INSTANCE in vec4 aClipLocalRect;
PER_INSTANCE in float aClipMode;
PER_INSTANCE in vec4 aClipRect_TL;
PER_INSTANCE in vec4 aClipRadii_TL;
PER_INSTANCE in vec4 aClipRect_TR;
PER_INSTANCE in vec4 aClipRadii_TR;
PER_INSTANCE in vec4 aClipRect_BL;
PER_INSTANCE in vec4 aClipRadii_BL;
PER_INSTANCE in vec4 aClipRect_BR;
PER_INSTANCE in vec4 aClipRadii_BR;
struct ClipMaskInstanceRect {
ClipMaskInstanceCommon base;
vec2 local_pos;
};
ClipMaskInstanceRect fetch_clip_item() {
ClipMaskInstanceRect cmi;
cmi.base = fetch_clip_item_common();
cmi.local_pos = aClipLocalPos;
return cmi;
}
struct ClipRect {
RectWithEndpoint rect;
float mode;
};
struct ClipCorner {
RectWithEndpoint rect;
vec4 outer_inner_radius;
};
struct ClipData {
ClipRect rect;
ClipCorner top_left;
ClipCorner top_right;
ClipCorner bottom_left;
ClipCorner bottom_right;
};
ClipData fetch_clip() {
ClipData clip;
clip.rect = ClipRect(RectWithEndpoint(aClipLocalRect.xy, aClipLocalRect.zw), aClipMo de);
clip.top_left = ClipCorner(RectWithEndpoint(aClipRect_TL.xy, aClipRect_TL.zw), aClipRadii_TL);
clip.top_right = ClipCorner(RectWithEndpoint(aClipRect_TR.xy, aClipRect_TR.zw), aClipRadii_TR);
clip.bottom_left = ClipCorner(RectWithEndpoint(aClipRect_BL.xy, aClipRect_BL.zw), aClipRadii_BL);
clip.bottom_right = ClipCorner(RectWithEndpoint(aClipRect_BR.xy, aClipRect_BR.zw), aClipRadii_BR);
return clip;
}
void main(void) {
ClipMaskInstanceRect cmi = fetch_clip_item();
Transform clip_transform = fetch_transform(cmi.base.clip_transform_id);
Transform prim_transform = fetch_transform(cmi.base.prim_transform_id);
ClipData clip = fetch_clip();
RectWithEndpoint local_rect = clip.rect.rect;
vec2 diff = cmi.local_pos - local_rect.p0;
local_rect.p0 = cmi.local_pos;
local_rect.p1 += diff;
ClipVertexInfo vi = write_clip_tile_vertex(
local_rect,
prim_transform,
clip_transform,
cmi.base.sub_rect,
cmi.base.task_origin,
cmi.base.screen_origin,
cmi.base.device_pixel_scale
);
vClipMode.x = clip.rect.mode;
vLocalPos = vi.local_pos;
#ifdef WR_FEATURE_FAST_PATH
// If the radii are all uniform, we can use a much simpler 2d
// signed distance function to get a rounded rect clip.
vec2 half_size = 0.5 * rect_size(local_rect);
vLocalPos.xy -= (half_size + cmi.local_pos) * vi.local_pos.w;
v_clip_size = half_size;
v_clip_radii = vec4(
clip.bottom_right.outer_inner_radius.x,
clip.top_right.outer_inner_radius.x,
clip.bottom_left.outer_inner_radius.x,
clip.top_left.outer_inner_radius.x
);
#else
RectWithEndpoint clip_rect = local_rect;
vec2 r_tl = clip.top_left.outer_inner_radius.xy;
vec2 r_tr = clip.top_right.outer_inner_radius.xy;
vec2 r_br = clip.bottom_right.outer_inner_radius.xy;
vec2 r_bl = clip.bottom_left.outer_inner_radius.xy;
vClipCenter_Radius_TL = vec4(clip_rect.p0 + r_tl,
inverse_radii_squared(r_tl));
vClipCenter_Radius_TR = vec4(clip_rect.p1.x - r_tr.x,
clip_rect.p0.y + r_tr.y,
inverse_radii_squared(r_tr));
vClipCenter_Radius_BR = vec4(clip_rect.p1 - r_br,
inverse_radii_squared(r_br));
vClipCenter_Radius_BL = vec4(clip_rect.p0.x + r_bl.x,
clip_rect.p1.y - r_bl.y,
inverse_radii_squared(r_bl));
// We need to know the half-spaces of the corners separate from the center
// and radius. We compute a point that falls on the diagonal (which is just
// an inner vertex pushed out along one axis, but not on both) to get the
// plane offset of the half-space. We also compute the direction vector of
// the half-space, which is a perpendicular vertex (-y,x) of the vector of
// the diagonal. We leave the scales of the vectors unchanged.
vec2 n_tl = -r_tl.yx;
vec2 n_tr = vec2(r_tr.y, -r_tr.x);
vec2 n_br = r_br.yx;
vec2 n_bl = vec2(-r_bl.y, r_bl.x);
vClipPlane_TL = vec3(n_tl,
dot(n_tl, vec2(clip_rect.p0.x, clip_rect.p0.y + r_tl.y)));
vClipPlane_TR = vec3(n_tr,
dot(n_tr, vec2(clip_rect.p1.x - r_tr.x, clip_rect.p0.y)));
vClipPlane_BR = vec3(n_br,
dot(n_br, vec2(clip_rect.p1.x, clip_rect.p1.y - r_br.y)));
vClipPlane_BL = vec3(n_bl,
dot(n_bl, vec2(clip_rect.p0.x + r_bl.x, clip_rect.p1.y)));
#endif
}
#endif
#ifdef WR_FRAGMENT_SHADER
#ifdef WR_FEATURE_FAST_PATH
// See https://www.shadertoy.com/view/4llXD7
// Notes:
// * pos is centered in the origin (so 0,0 is the center of the box).
// * The border radii must not be larger than half_box_size.
float sd_round_box(in vec2 pos, in vec2 half_box_size, in vec4 radii) {
radii.xy = (pos.x > 0.0) ? radii.xy : radii.zw;
radii.x = (pos.y > 0.0) ? radii.x : radii.y;
vec2 q = abs(pos) - half_box_size + radii.x;
return min(max(q.x, q.y), 0.0) + length(max(q, 0.0)) - radii.x;
}
#endif
void main(void) {
vec2 local_pos = vLocalPos.xy / vLocalPos.w;
float aa_range = compute_aa_range(local_pos);
#ifdef WR_FEATURE_FAST_PATH
float dist = sd_round_box(local_pos, v_clip_size, v_clip_radii);
#else
float dist = distance_to_rounded_rect(
local_pos,
vClipPlane_TL,
vClipCenter_Radius_TL,
vClipPlane_TR,
vClipCenter_Radius_TR,
vClipPlane_BR,
vClipCenter_Radius_BR,
vClipPlane_BL,
vClipCenter_Radius_BL,
vTransformBounds
);
#endif
// Compute AA for the given dist and range.
float alpha = distance_aa(aa_range, dist);
// Select alpha or inverse alpha depending on clip in/out.
float final_alpha = mix(alpha, 1.0 - alpha, vClipMode.x);
float final_final_alpha = vLocalPos.w > 0.0 ? final_alpha : 0.0;
oFragColor = vec4(final_final_alpha, 0.0, 0.0, 1.0);
}
#ifdef SWGL_DRAW_SPAN
// Currently the cs_clip_rectangle shader is slow because it always evaluates
// the corner ellipse segments and the rectangle AA for every fragment the
// shader is run on. To alleviate this for now with SWGL, this essentially
// implements a rounded-rectangle span rasterizer inside the span shader. The
// motivation is that we can separate out the parts of the span which are fully
// opaque and fully transparent, outputting runs of fixed color in those areas,
// while only evaluating the ellipse segments and AA in the smaller outlying
// parts of the span that actually need it.
// The shader conceptually represents a rounded rectangle as an inner octagon
// (8 half-spaces) bounding the opaque region and an outer octagon bounding the
// curve and AA parts. Everything outside is transparent. The line of the span
// is intersected with half-spaces, looking for interior spans that minimally
// intersect the half-spaces (start max, end min). In the ideal case we hit a
// start corner ellipse segment and an end corner ellipse segment, rendering
// the two curves on the ends with an opaque run in between, outputting clear
// for any transparent runs before and after the start and end curves.
// This is slightly complicated by the fact that the results here must agree
// with the main results of the fragment shader, in case SWGL has to fall back
// to the main fragment shader for any reason. So, we make an effort to handle
// both ways of operating - the uniform radius fast-path and the varying radius
// slow-path.
void swgl_drawSpanR8() {
// Perspective is not supported.
if (swgl_interpStep(vLocalPos).w != 0.0) {
return;
}
// If the span is completely outside the Z-range and clipped out, just
// output clear so we don't need to consider invalid W in the rest of the
// shader.
float w = swgl_forceScalar(vLocalPos.w);
if (w <= 0.0) {
swgl_commitSolidR8(0.0);
return;
}
// To start, we evaluate the rounded-rectangle in local space relative to
// the local-space position. This will be interpolated across the span to
// track whether we intersect any half-spaces.
w = 1.0 / w;
vec2 local_pos = vLocalPos.xy * w;
vec2 local_pos0 = swgl_forceScalar(local_pos);
vec2 local_step = swgl_interpStep(vLocalPos).xy * w;
float step_scale = max(dot(local_step, local_step), 1.0e-6);
// Get the local-space AA range. This range represents 1/fwidth(local_pos),
// essentially the scale of how much local-space maps to an AA pixel. We
// need to know the inverse, how much local-space we traverse per AA pixel
// pixel step. We then scale this to represent the amount of span steps
// traversed per AA pixel step.
float aa_range = compute_aa_range(local_pos);
float aa_margin = inversesqrt(aa_range * aa_range * step_scale);
// We need to know the bounds of the aligned rectangle portion of the rrect
// in local-space. If we're using the fast-path, this is specified as the
// half-width of the rrect in v_clip_size, which we map to the outer
// bounding-box. For the general case, we have already stored the outer
// bounding box in vTransformBounds.
#ifdef WR_FEATURE_FAST_PATH
vec4 clip_rect = vec4(-v_clip_size, v_clip_size);
#else
vec4 clip_rect = vTransformBounds;
#endif
// We need to compute the local-space distance to the bounding box and then
// figure out how many processing steps that maps to. If we are stepping in
// a negative direction on an axis, we need to swap the sides of the box
// which we consider as the start or end. If there is no local-space step
// on an axis (i.e. constant Y), we need to take care to force the steps to
// either the start or end of the span depending on if we are inside or
// outside of the bounding box.
vec4 clip_dist =
mix(clip_rect, clip_rect.zwxy, lessThan(local_step, vec2(0.0)).xyxy)
- local_pos0.xyxy;
clip_dist =
mix(1.0e6 * step(0.0, clip_dist),
clip_dist * recip(local_step).xyxy,
notEqual(local_step, vec2(0.0)).xyxy);
// Initially, the opaque region is bounded by the further start intersect
// with the bounding box and the nearest end intersect with the bounding
// box.
float opaque_start = max(clip_dist.x, clip_dist.y);
float opaque_end = min(clip_dist.z, clip_dist.w);
float aa_start = opaque_start;
float aa_end = opaque_end;
// Here we actually intersect with the half-space of the corner. We get the
// plane distance of the local-space position from the diagonal bounding
// ellipse segment from the opaque region. The half-space is defined by the
// direction vector of the plane and an offset point that falls on the
// dividing line (which is a vertex on the corner box, which is actually on
// the outer radius of the bounding box, but not a corner vertex). This
// distance is positive if on the curve side and negative if on the inner
// opaque region. If we are on the curve side, we need to verify we are
// traveling in direction towards the opaque region so that we will
// eventually intersect the diagonal so we can calculate when the start
// corner segment will end, otherwise we are going away from the rrect.
// If we are inside the opaque interior, we need to verify we are traveling
// in direction towards the curve, so that we can calculate when the end
// corner segment will start. Further, if we intersect, we calculate the
// offset of the outer octagon where AA starts from the inner octagon of
// where the opaque region starts using the apex vector (which is transpose
// of the half-space's direction).
//
// We need to intersect the corner ellipse segments. Significantly, we need
// to know where the apex of the ellipse segment is and how far to push the
// outer diagonal of the octagon from the inner diagonal. The position of
// the inner diagonal simply runs diagonal across the corner box and has a
// constant offset from vertex on the inner bounding box. The apex also has
// a constant offset along the opposite diagonal relative to the diagonal
// intersect which is 1/sqrt(2) - 0.5 assuming unit length for the diagonal.
// We then need to project the vector to the apex onto the local-space step
// scale, but we do this with reference to the normal vector of the diagonal
// using dot(normal, apex) / dot(normal, local_step), where the apex vector
// is (0.7071 - 0.5) * abs(normal).yx * sign(normal).
vec3 start_plane = vec3(1.0e6);
vec3 end_plane = vec3(1.0e6);
// plane is assumed to be a vec3 with normal in (X, Y) and offset in Z.
#define CLIP_CORNER(plane, info) do { \
float dist = dot(local_pos0, plane.xy) - plane.z; \
float scale = -dot(local_step, plane.xy); \
if (scale >= 0.0) { \
if (dist > opaque_start * scale) { \
SET_CORNER(start_corner, info); \
start_plane = plane; \
float inv_scale = recip(max(scale, 1.0e-6)); \
opaque_start = dist * inv_scale; \
float apex = (0.7071 - 0.5) * 2.0 * abs(plane.x * plane.y); \
aa_start = opaque_start - apex * inv_scale; \
} \
} else if (dist > opaque_end * scale) { \
SET_CORNER(end_corner, info); \
end_plane = plane; \
float inv_scale = recip(min(scale, -1.0e-6)); \
opaque_end = dist * inv_scale; \
float apex = (0.7071 - 0.5) * 2.0 * abs(plane.x * plane.y); \
aa_end = opaque_end - apex * inv_scale; \
} \
} while (false)
#ifdef WR_FEATURE_FAST_PATH
// For the fast-path, we only have the half-width of the outer bounding
// box. We need to map this to points that fall on the diagonal of the
// half-space for each corner. To do this we just need to push out the
// vertex in the right direction on a single axis, leaving the other
// unchanged.
// However, since the corner radii are symmetric, and since the local
// origin of each ellipse is assumed to be at (0, 0), the plane offset
// of the half-space is similar for each case.
// So for a given corner radii of z, given a corner offset (x, y - z)
// and a vector of (z, z), the dot product becomes:
// x * z + (y-z)*z == x*z + y*z - z*z
// The direction vector of the corner half-space has constant length,
// but just needs an appropriate direction set.
#define OFFSET_FOR(radii) \
(v_clip_size.x + v_clip_size.y - radii) * radii
vec3 plane_br = vec3(v_clip_radii.xx, OFFSET_FOR(v_clip_radii.x));
vec3 plane_tr = vec3(v_clip_radii.y, -v_clip_radii.y, OFFSET_FOR(v_clip_radii.y));
vec3 plane_bl = vec3(-v_clip_radii.z, v_clip_radii.z, OFFSET_FOR(v_clip_radii.z));
vec3 plane_tl = vec3(-v_clip_radii.ww, OFFSET_FOR(v_clip_radii.w));
#define SET_CORNER(corner, info)
// Clip against the corner half-spaces.
CLIP_CORNER(plane_tl, );
CLIP_CORNER(plane_tr, );
CLIP_CORNER(plane_br, );
CLIP_CORNER(plane_bl, );
// Later we need to calculate distance AA for both corners and the
// outer bounding rect. For the fast-path, this is all done inside
// sd_round_box.
#define AA_RECT(local_pos) \
sd_round_box(local_pos, v_clip_size, v_clip_radii)
#else
// For the general case, we need to remember which of the actual start
// and end corners we intersect, so that we can evaluate the curve AA
// against only those corners rather than having to try against all 4
// corners for both sides of the span. Initialize these values so that
// if no corner is intersected, they will just zero the AA.
vec4 start_corner = vec4(vec2(1.0e6), vec2(1.0));
vec4 end_corner = vec4(vec2(1.0e6), vec2(1.0));
#define SET_CORNER(corner, info) corner = info
// Clip against the corner half-spaces. We have already computed the
// corner half-spaces in the vertex shader.
CLIP_CORNER(vClipPlane_TL, vClipCenter_Radius_TL);
CLIP_CORNER(vClipPlane_TR, vClipCenter_Radius_TR);
CLIP_CORNER(vClipPlane_BR, vClipCenter_Radius_BR);
CLIP_CORNER(vClipPlane_BL, vClipCenter_Radius_BL);
// Later we need to calculate distance AA for both corners and the
// outer bounding rect. For the general case, we need to explicitly
// evaluate either the ellipse segment distance or the rect distance.
#define AA_RECT(local_pos) \
signed_distance_rect(local_pos, vTransformBounds.xy, vTransformBounds.zw)
#define AA_CORNER(local_pos, corner) \
distance_to_ellipse_approx(local_pos - corner.xy, corner.zw, 1.0)
#endif
// Pad the AA region by a margin, as the intersections take place assuming
// pixel centers, but AA actually starts half a pixel away from the center.
// If the AA region narrows to nothing, be careful not to inflate so much
// that we start processing AA for fragments that don't need it.
aa_margin = max(aa_margin - max(aa_start - aa_end, 0.0), 0.0);
aa_start -= aa_margin;
aa_end += aa_margin;
// Compute the thresholds at which we need to transition between various
// segments of the span, from fully transparent outside to the start of
// the outer octagon where AA starts, from there to where the inner opaque
// octagon starts, from there to where the opaque inner octagon ends and
// AA starts again, to finally where the outer octagon/AA ends and we're
// back to fully transparent. These thresholds are just flipped offsets
// from the start of the span so we can compare against the remaining
// span length which automatically deducts as we commit fragments.
ivec4 steps = ivec4(clamp(
swgl_SpanLength -
swgl_StepSize *
vec4(floor(aa_start), ceil(opaque_start), floor(opaque_end), ceil(aa_end)),
0.0, swgl_SpanLength));
int aa_start_len = steps.x;
int opaque_start_len = steps.y;
int opaque_end_len = steps.z;
int aa_end_len = steps.w;
// Output fully clear while we're outside the AA region.
if (swgl_SpanLength > aa_start_len) {
int num_aa = swgl_SpanLength - aa_start_len;
swgl_commitPartialSolidR8(num_aa, vClipMode.x);
local_pos += float(num_aa / swgl_StepSize) * local_step;
}
#ifdef AA_CORNER
if (start_plane.x < 1.0e5) {
// We're now in the outer octagon which requires AA. Evaluate the corner
// distance of the start corner here and output AA for it. Before we hit
// the actual opaque inner octagon, we have a transitional step where the
// diagonal might intersect mid-way through the step. We have consider
// either the corner or rect distance depending on which side we're on.
while (swgl_SpanLength > opaque_start_len) {
float alpha = distance_aa(aa_range,
dot(local_pos, start_plane.xy) > start_plane.z
? AA_CORNER(local_pos, start_corner)
: AA_RECT(local_pos));
swgl_commitColorR8(mix(alpha, 1.0 - alpha, vClipMode.x));
local_pos += local_step;
}
}
#endif
// If there's no start corner, just do rect AA until opaque.
while (swgl_SpanLength > opaque_start_len) {
float alpha = distance_aa(aa_range, AA_RECT(local_pos));
swgl_commitColorR8(mix(alpha, 1.0 - alpha, vClipMode.x));
local_pos += local_step;
}
// Now we're finally in the opaque inner octagon part of the span. Just
// output a solid run.
if (swgl_SpanLength > opaque_end_len) {
int num_opaque = swgl_SpanLength - opaque_end_len;
swgl_commitPartialSolidR8(num_opaque, 1.0 - vClipMode.x);
local_pos += float(num_opaque / swgl_StepSize) * local_step;
}
#ifdef AA_CORNER
if (end_plane.x < 1.0e5) {
// Finally we're in the AA region on the other side, inside the outer
// octagon again. Just evaluate the distance to the end corner and
// compute AA for it. We're leaving the opaque inner octagon, but like
// before, we have to be careful we're not dealing with a step partially
// intersected by the end corner's diagonal. Check which side we are on
// and use either the corner or rect distance as appropriate.
while (swgl_SpanLength > aa_end_len) {
float alpha = distance_aa(aa_range,
dot(local_pos, end_plane.xy) > end_plane.z
? AA_CORNER(local_pos, end_corner)
: AA_RECT(local_pos));
swgl_commitColorR8(mix(alpha, 1.0 - alpha, vClipMode.x));
local_pos += local_step;
}
}
#endif
// If there's no end corner, just do rect AA until clear.
while (swgl_SpanLength > aa_end_len) {
float alpha = distance_aa(aa_range, AA_RECT(local_pos));
swgl_commitColorR8(mix(alpha, 1.0 - alpha, vClipMode.x));
local_pos += local_step;
}
// We're now outside the outer AA octagon on the other side. Just output
// fully clear.
if (swgl_SpanLength > 0) {
swgl_commitPartialSolidR8(swgl_SpanLength, vClipMode.x);
}
}
#endif
#endif
[ Dauer der Verarbeitung: 0.17 Sekunden
(vorverarbeitet)
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2026-04-06
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