linux: shadow rendering
This commit is contained in:
Dzmitry Malyshau
parent
ecf4955899
commit
666b134d20
9 changed files with 236 additions and 62 deletions
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@ -1,3 +1,17 @@
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struct Globals {
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viewport_size: vec2<f32>,
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pad: vec2<u32>,
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}
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var<uniform> globals: Globals;
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const M_PI_F: f32 = 3.1415926;
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struct ViewId {
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lo: u32,
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hi: u32,
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}
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struct Bounds {
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origin: vec2<f32>,
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size: vec2<f32>,
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@ -21,35 +35,6 @@ struct Hsla {
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a: f32,
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}
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struct Quad {
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view_id: vec2<u32>,
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layer_id: u32,
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order: u32,
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bounds: Bounds,
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content_mask: Bounds,
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background: Hsla,
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border_color: Hsla,
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corner_radii: Corners,
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border_widths: Edges,
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}
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struct Globals {
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viewport_size: vec2<f32>,
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pad: vec2<u32>,
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}
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var<uniform> globals: Globals;
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var<storage, read> quads: array<Quad>;
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struct QuadsVarying {
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@builtin(position) position: vec4<f32>,
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@location(0) @interpolate(flat) background_color: vec4<f32>,
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@location(1) @interpolate(flat) border_color: vec4<f32>,
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@location(2) @interpolate(flat) quad_id: u32,
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//TODO: use `clip_distance` once Naga supports it
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@location(3) clip_distances: vec4<f32>,
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}
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fn to_device_position(unit_vertex: vec2<f32>, bounds: Bounds) -> vec4<f32> {
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let position = unit_vertex * vec2<f32>(bounds.size) + bounds.origin;
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let device_position = position / globals.viewport_size * vec2<f32>(2.0, -2.0) + vec2<f32>(-1.0, 1.0);
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@ -99,17 +84,62 @@ fn hsla_to_rgba(hsla: Hsla) -> vec4<f32> {
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}
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fn over(below: vec4<f32>, above: vec4<f32>) -> vec4<f32> {
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let alpha = above.a + below.a * (1.0 - above.a);
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let color = (above.rgb * above.a + below.rgb * below.a * (1.0 - above.a)) / alpha;
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return vec4<f32>(color, alpha);
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let alpha = above.a + below.a * (1.0 - above.a);
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let color = (above.rgb * above.a + below.rgb * below.a * (1.0 - above.a)) / alpha;
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return vec4<f32>(color, alpha);
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}
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// A standard gaussian function, used for weighting samples
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fn gaussian(x: f32, sigma: f32) -> f32{
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return exp(-(x * x) / (2.0 * sigma * sigma)) / (sqrt(2.0 * M_PI_F) * sigma);
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}
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// This approximates the error function, needed for the gaussian integral
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fn erf(v: vec2<f32>) -> vec2<f32> {
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let s = sign(v);
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let a = abs(v);
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let r1 = 1.0 + (0.278393 + (0.230389 + 0.078108 * (a * a)) * a) * a;
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let r2 = r1 * r1;
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return s - s / (r2 * r2);
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}
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fn blur_along_x(x: f32, y: f32, sigma: f32, corner: f32, half_size: vec2<f32>) -> f32 {
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let delta = min(half_size.y - corner - abs(y), 0.0);
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let curved = half_size.x - corner + sqrt(max(0.0, corner * corner - delta * delta));
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let integral = 0.5 + 0.5 * erf((x + vec2<f32>(-curved, curved)) * (sqrt(0.5) / sigma));
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return integral.y - integral.x;
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}
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// --- quads --- //
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struct Quad {
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view_id: ViewId,
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layer_id: u32,
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order: u32,
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bounds: Bounds,
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content_mask: Bounds,
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background: Hsla,
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border_color: Hsla,
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corner_radii: Corners,
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border_widths: Edges,
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}
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var<storage, read> b_quads: array<Quad>;
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struct QuadVarying {
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@builtin(position) position: vec4<f32>,
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@location(0) @interpolate(flat) background_color: vec4<f32>,
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@location(1) @interpolate(flat) border_color: vec4<f32>,
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@location(2) @interpolate(flat) quad_id: u32,
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//TODO: use `clip_distance` once Naga supports it
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@location(3) clip_distances: vec4<f32>,
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}
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@vertex
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fn vs_quads(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) instance_id: u32) -> QuadsVarying {
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fn vs_quad(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) instance_id: u32) -> QuadVarying {
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let unit_vertex = vec2<f32>(f32(vertex_id & 1u), 0.5 * f32(vertex_id & 2u));
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let quad = quads[instance_id];
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let quad = b_quads[instance_id];
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var out = QuadsVarying();
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var out = QuadVarying();
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out.position = to_device_position(unit_vertex, quad.bounds);
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out.background_color = hsla_to_rgba(quad.background);
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out.border_color = hsla_to_rgba(quad.border_color);
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@ -119,7 +149,7 @@ fn vs_quads(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) inst
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}
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@fragment
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fn fs_quads(input: QuadsVarying) -> @location(0) vec4<f32> {
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fn fs_quad(input: QuadVarying) -> @location(0) vec4<f32> {
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// Alpha clip first, since we don't have `clip_distance`.
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let min_distance = min(
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min(input.clip_distances.x, input.clip_distances.y),
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@ -129,7 +159,7 @@ fn fs_quads(input: QuadsVarying) -> @location(0) vec4<f32> {
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return vec4<f32>(0.0);
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}
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let quad = quads[input.quad_id];
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let quad = b_quads[input.quad_id];
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let half_size = quad.bounds.size / 2.0;
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let center = quad.bounds.origin + half_size;
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let center_to_point = input.position.xy - center;
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@ -180,4 +210,98 @@ fn fs_quads(input: QuadsVarying) -> @location(0) vec4<f32> {
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}
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return color * vec4<f32>(1.0, 1.0, 1.0, saturate(0.5 - distance));
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}
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}
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// --- shadows --- //
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struct Shadow {
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view_id: ViewId,
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layer_id: u32,
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order: u32,
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bounds: Bounds,
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corner_radii: Corners,
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content_mask: Bounds,
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color: Hsla,
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blur_radius: f32,
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pad: u32,
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}
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var<storage, read> b_shadows: array<Shadow>;
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struct ShadowVarying {
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@builtin(position) position: vec4<f32>,
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@location(0) @interpolate(flat) color: vec4<f32>,
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@location(1) @interpolate(flat) shadow_id: u32,
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//TODO: use `clip_distance` once Naga supports it
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@location(3) clip_distances: vec4<f32>,
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}
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@vertex
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fn vs_shadow(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) instance_id: u32) -> ShadowVarying {
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let unit_vertex = vec2<f32>(f32(vertex_id & 1u), 0.5 * f32(vertex_id & 2u));
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let shadow = b_shadows[instance_id];
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let margin = 3.0 * shadow.blur_radius;
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// Set the bounds of the shadow and adjust its size based on the shadow's
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// spread radius to achieve the spreading effect
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var bounds = shadow.bounds;
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bounds.origin -= vec2<f32>(margin);
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bounds.size += 2.0 * vec2<f32>(margin);
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var out = ShadowVarying();
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out.position = to_device_position(unit_vertex, shadow.bounds);
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out.color = hsla_to_rgba(shadow.color);
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out.shadow_id = instance_id;
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out.clip_distances = distance_from_clip_rect(unit_vertex, shadow.bounds, shadow.content_mask);
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return out;
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}
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@fragment
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fn fs_shadow(input: ShadowVarying) -> @location(0) vec4<f32> {
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// Alpha clip first, since we don't have `clip_distance`.
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let min_distance = min(
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min(input.clip_distances.x, input.clip_distances.y),
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min(input.clip_distances.z, input.clip_distances.w)
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);
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if min_distance <= 0.0 {
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return vec4<f32>(0.0);
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}
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let shadow = b_shadows[input.shadow_id];
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let half_size = shadow.bounds.size / 2.0;
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let center = shadow.bounds.origin + half_size;
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let center_to_point = input.position.xy - center;
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var corner_radius = 0.0;
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if (center_to_point.x < 0.0) {
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if (center_to_point.y < 0.0) {
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corner_radius = shadow.corner_radii.top_left;
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} else {
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corner_radius = shadow.corner_radii.bottom_left;
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}
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} else {
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if (center_to_point.y < 0.) {
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corner_radius = shadow.corner_radii.top_right;
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} else {
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corner_radius = shadow.corner_radii.bottom_right;
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}
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}
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// The signal is only non-zero in a limited range, so don't waste samples
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let low = center_to_point.y - half_size.y;
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let high = center_to_point.y + half_size.y;
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let start = clamp(-3.0 * shadow.blur_radius, low, high);
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let end = clamp(3.0 * shadow.blur_radius, low, high);
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// Accumulate samples (we can get away with surprisingly few samples)
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let step = (end - start) / 4.0;
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var y = start + step * 0.5;
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var alpha = 0.0;
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for (var i = 0; i < 4; i += 1) {
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let blur = blur_along_x(center_to_point.x, center_to_point.y - y,
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shadow.blur_radius, corner_radius, half_size);
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alpha += blur * gaussian(y, shadow.blur_radius) * step;
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y += step;
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}
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return input.color * vec4<f32>(1.0, 1.0, 1.0, alpha);
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}
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