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// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
// This is "kernel 4" in a 4-kernel pipeline. It renders the commands
// in the per-tile command list to an image.
// Right now, this kernel stores the image in a buffer, but a better
// plan is to use a texture. This is because of limited support.
#version 450
#extension GL_GOOGLE_include_directive : enable
#ifdef ENABLE_IMAGE_INDICES
#extension GL_EXT_nonuniform_qualifier : enable
#endif
#include "mem.h"
#include "setup.h"
#define CHUNK_X 2
#define CHUNK_Y 4
#define CHUNK CHUNK_X * CHUNK_Y
#define CHUNK_DX (TILE_WIDTH_PX / CHUNK_X)
#define CHUNK_DY (TILE_HEIGHT_PX / CHUNK_Y)
layout(local_size_x = CHUNK_DX, local_size_y = CHUNK_DY) in;
layout(set = 0, binding = 1) restrict readonly buffer ConfigBuf {
Config conf;
};
layout(rgba8, set = 0, binding = 2) uniform restrict writeonly image2D image;
#ifdef ENABLE_IMAGE_INDICES
layout(rgba8, set = 0, binding = 3) uniform restrict readonly image2D images[];
#else
layout(rgba8, set = 0, binding = 3) uniform restrict readonly image2D images;
#endif
#include "ptcl.h"
#include "tile.h"
mediump vec3 tosRGB(mediump vec3 rgb) {
bvec3 cutoff = greaterThanEqual(rgb, vec3(0.0031308));
mediump vec3 below = vec3(12.92)*rgb;
mediump vec3 above = vec3(1.055)*pow(rgb, vec3(0.41666)) - vec3(0.055);
return mix(below, above, cutoff);
}
mediump vec3 fromsRGB(mediump vec3 srgb) {
// Formula from EXT_sRGB.
bvec3 cutoff = greaterThanEqual(srgb, vec3(0.04045));
mediump vec3 below = srgb/vec3(12.92);
mediump vec3 above = pow((srgb + vec3(0.055))/vec3(1.055), vec3(2.4));
return mix(below, above, cutoff);
}
// unpacksRGB unpacks a color in the sRGB color space to a vec4 in the linear color
// space.
mediump vec4 unpacksRGB(uint srgba) {
mediump vec4 color = unpackUnorm4x8(srgba).wzyx;
return vec4(fromsRGB(color.rgb), color.a);
}
// packsRGB packs a color in the linear color space into its 8-bit sRGB equivalent.
uint packsRGB(mediump vec4 rgba) {
rgba = vec4(tosRGB(rgba.rgb), rgba.a);
return packUnorm4x8(rgba.wzyx);
}
uvec2 chunk_offset(uint i) {
return uvec2(i % CHUNK_X * CHUNK_DX, i / CHUNK_X * CHUNK_DY);
}
mediump vec4[CHUNK] fillImage(uvec2 xy, CmdImage cmd_img) {
mediump vec4 rgba[CHUNK];
for (uint i = 0; i < CHUNK; i++) {
ivec2 uv = ivec2(xy + chunk_offset(i)) + cmd_img.offset;
mediump vec4 fg_rgba;
#ifdef ENABLE_IMAGE_INDICES
fg_rgba = imageLoad(images[cmd_img.index], uv);
#else
fg_rgba = imageLoad(images, uv);
#endif
fg_rgba.rgb = fromsRGB(fg_rgba.rgb);
rgba[i] = fg_rgba;
}
return rgba;
}
void main() {
uint tile_ix = gl_WorkGroupID.y * conf.width_in_tiles + gl_WorkGroupID.x;
Alloc cmd_alloc = slice_mem(conf.ptcl_alloc, tile_ix * PTCL_INITIAL_ALLOC, PTCL_INITIAL_ALLOC);
CmdRef cmd_ref = CmdRef(cmd_alloc.offset);
// Read scrach space allocation, written first in the command list.
Alloc scratch_alloc = alloc_read(cmd_alloc, cmd_ref.offset);
cmd_ref.offset += Alloc_size;
uvec2 xy_uint = uvec2(gl_LocalInvocationID.x + TILE_WIDTH_PX * gl_WorkGroupID.x, gl_LocalInvocationID.y + TILE_HEIGHT_PX * gl_WorkGroupID.y);
vec2 xy = vec2(xy_uint);
mediump vec4 rgba[CHUNK];
for (uint i = 0; i < CHUNK; i++) {
rgba[i] = vec4(0.0);
// TODO: remove this debug image support when the actual image method is plumbed.
#ifdef DEBUG_IMAGES
#ifdef ENABLE_IMAGE_INDICES
if (xy_uint.x < 1024 && xy_uint.y < 1024) {
rgba[i] = imageLoad(images[gl_WorkGroupID.x / 64], ivec2(xy_uint + chunk_offset(i))/4);
}
#else
if (xy_uint.x < 1024 && xy_uint.y < 1024) {
rgb[i] = imageLoad(images[0], ivec2(xy_uint + chunk_offset(i))/4).rgb;
}
#endif
#endif
}
mediump float area[CHUNK];
uint clip_depth = 0;
bool mem_ok = mem_error == NO_ERROR;
while (mem_ok) {
uint tag = Cmd_tag(cmd_alloc, cmd_ref).tag;
if (tag == Cmd_End) {
break;
}
switch (tag) {
case Cmd_Stroke:
// Calculate distance field from all the line segments in this tile.
CmdStroke stroke = Cmd_Stroke_read(cmd_alloc, cmd_ref);
mediump float df[CHUNK];
for (uint k = 0; k < CHUNK; k++) df[k] = 1e9;
TileSegRef tile_seg_ref = TileSegRef(stroke.tile_ref);
do {
TileSeg seg = TileSeg_read(new_alloc(tile_seg_ref.offset, TileSeg_size, mem_ok), tile_seg_ref);
vec2 line_vec = seg.vector;
for (uint k = 0; k < CHUNK; k++) {
vec2 dpos = xy + vec2(0.5, 0.5) - seg.origin;
dpos += vec2(chunk_offset(k));
float t = clamp(dot(line_vec, dpos) / dot(line_vec, line_vec), 0.0, 1.0);
df[k] = min(df[k], length(line_vec * t - dpos));
}
tile_seg_ref = seg.next;
} while (tile_seg_ref.offset != 0);
for (uint k = 0; k < CHUNK; k++) {
area[k] = clamp(stroke.half_width + 0.5 - df[k], 0.0, 1.0);
}
cmd_ref.offset += 4 + CmdStroke_size;
break;
case Cmd_Fill:
CmdFill fill = Cmd_Fill_read(cmd_alloc, cmd_ref);
for (uint k = 0; k < CHUNK; k++) area[k] = float(fill.backdrop);
tile_seg_ref = TileSegRef(fill.tile_ref);
// Calculate coverage based on backdrop + coverage of each line segment
do {
TileSeg seg = TileSeg_read(new_alloc(tile_seg_ref.offset, TileSeg_size, mem_ok), tile_seg_ref);
for (uint k = 0; k < CHUNK; k++) {
vec2 my_xy = xy + vec2(chunk_offset(k));
vec2 start = seg.origin - my_xy;
vec2 end = start + seg.vector;
vec2 window = clamp(vec2(start.y, end.y), 0.0, 1.0);
if (window.x != window.y) {
vec2 t = (window - start.y) / seg.vector.y;
vec2 xs = vec2(mix(start.x, end.x, t.x), mix(start.x, end.x, t.y));
float xmin = min(min(xs.x, xs.y), 1.0) - 1e-6;
float xmax = max(xs.x, xs.y);
float b = min(xmax, 1.0);
float c = max(b, 0.0);
float d = max(xmin, 0.0);
float a = (b + 0.5 * (d * d - c * c) - xmin) / (xmax - xmin);
area[k] += a * (window.x - window.y);
}
area[k] += sign(seg.vector.x) * clamp(my_xy.y - seg.y_edge + 1.0, 0.0, 1.0);
}
tile_seg_ref = seg.next;
} while (tile_seg_ref.offset != 0);
for (uint k = 0; k < CHUNK; k++) {
area[k] = min(abs(area[k]), 1.0);
}
cmd_ref.offset += 4 + CmdFill_size;
break;
case Cmd_Solid:
for (uint k = 0; k < CHUNK; k++) {
area[k] = 1.0;
}
cmd_ref.offset += 4;
break;
case Cmd_Alpha:
CmdAlpha alpha = Cmd_Alpha_read(cmd_alloc, cmd_ref);
for (uint k = 0; k < CHUNK; k++) {
area[k] = alpha.alpha;
}
cmd_ref.offset += 4 + CmdAlpha_size;
break;
case Cmd_Color:
CmdColor color = Cmd_Color_read(cmd_alloc, cmd_ref);
mediump vec4 fg = unpacksRGB(color.rgba_color);
for (uint k = 0; k < CHUNK; k++) {
mediump vec4 fg_k = fg * area[k];
rgba[k] = rgba[k] * (1.0 - fg_k.a) + fg_k;
}
cmd_ref.offset += 4 + CmdColor_size;
break;
case Cmd_Image:
CmdImage fill_img = Cmd_Image_read(cmd_alloc, cmd_ref);
mediump vec4 img[CHUNK] = fillImage(xy_uint, fill_img);
for (uint k = 0; k < CHUNK; k++) {
mediump vec4 fg_k = img[k] * area[k];
rgba[k] = rgba[k] * (1.0 - fg_k.a) + fg_k;
}
cmd_ref.offset += 4 + CmdImage_size;
break;
case Cmd_BeginClip:
uint base_ix = (scratch_alloc.offset >> 2) + CLIP_STATE_SIZE * (clip_depth * TILE_WIDTH_PX * TILE_HEIGHT_PX +
gl_LocalInvocationID.x + TILE_WIDTH_PX * gl_LocalInvocationID.y);
for (uint k = 0; k < CHUNK; k++) {
uvec2 offset = chunk_offset(k);
uint srgb = packsRGB(vec4(rgba[k]));
mediump float alpha = clamp(abs(area[k]), 0.0, 1.0);
write_mem(scratch_alloc, base_ix + 0 + CLIP_STATE_SIZE * (offset.x + offset.y * TILE_WIDTH_PX), srgb);
write_mem(scratch_alloc, base_ix + 1 + CLIP_STATE_SIZE * (offset.x + offset.y * TILE_WIDTH_PX), floatBitsToUint(alpha));
rgba[k] = vec4(0.0);
}
clip_depth++;
cmd_ref.offset += 4;
break;
case Cmd_EndClip:
clip_depth--;
base_ix = (scratch_alloc.offset >> 2) + CLIP_STATE_SIZE * (clip_depth * TILE_WIDTH_PX * TILE_HEIGHT_PX +
gl_LocalInvocationID.x + TILE_WIDTH_PX * gl_LocalInvocationID.y);
for (uint k = 0; k < CHUNK; k++) {
uvec2 offset = chunk_offset(k);
uint srgb = read_mem(scratch_alloc, base_ix + 0 + CLIP_STATE_SIZE * (offset.x + offset.y * TILE_WIDTH_PX));
uint alpha = read_mem(scratch_alloc, base_ix + 1 + CLIP_STATE_SIZE * (offset.x + offset.y * TILE_WIDTH_PX));
mediump vec4 bg = unpacksRGB(srgb);
mediump vec4 fg = rgba[k] * area[k] * uintBitsToFloat(alpha);
rgba[k] = bg * (1.0 - fg.a) + fg;
}
cmd_ref.offset += 4;
break;
case Cmd_Jump:
cmd_ref = CmdRef(Cmd_Jump_read(cmd_alloc, cmd_ref).new_ref);
cmd_alloc.offset = cmd_ref.offset;
break;
}
}
for (uint i = 0; i < CHUNK; i++) {
imageStore(image, ivec2(xy_uint + chunk_offset(i)), vec4(tosRGB(rgba[i].rgb), rgba[i].a));
}
}
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