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[Impeller] Add direct tesselation of circles for DrawCircle and Round end caps #48103

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auto-submit merged 9 commits into from
Nov 30, 2023
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[Impeller] Add direct tesselation of circles for DrawCircle and Round end caps #48103

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72d57eb
[Impeller] Add direct tesselation of circles for DrawCircle and Round…
flar Nov 16, 2023
63ea32b
switch to triangle strips for circles and simplify tessellation API
flar Nov 17, 2023
d498124
Fix old naming typos in comments
flar Nov 17, 2023
cab69d8
simplify vertex accumulation
flar Nov 22, 2023
cfca2e1
re-enable GPU compute tessellator for PointFields
flar Nov 22, 2023
4b638ba
move to direct HostBuffer emplacement of tessellation results
flar Nov 22, 2023
4ccdb46
Move CircleTessellator to tessellator dir and move cache to Tessellat…
flar Nov 30, 2023
aeef542
document and refine circle division computation
flar Nov 30, 2023
16fa52d
style feedback from review
flar Nov 30, 2023
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move to direct HostBuffer emplacement of tessellation results
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@flar
flar committed Nov 30, 2023
commit 4b638ba6f8add217c2a37d7046f8c8e0027cb652
11 changes: 6 additions & 5 deletions impeller/entity/geometry/circle_tessellator.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@

namespace impeller {

std::vector<Trig> CircleTessellator::trigs_[MAX_DIVISIONS_ + 1];
std::vector<Trig> CircleTessellator::trigs_[kMaxDivisions + 1];

size_t CircleTessellator::ComputeQuadrantDivisions(Scalar pixel_radius) {
// Note: these values are approximated based on the values returned from
Expand All @@ -26,16 +26,17 @@ size_t CircleTessellator::ComputeQuadrantDivisions(Scalar pixel_radius) {
return 9;
}
pixel_radius /= 4;
if (pixel_radius > (MAX_DIVISIONS_ - 1)) {
return MAX_DIVISIONS_;
if (pixel_radius > (kMaxDivisions - 1)) {
return kMaxDivisions;
}
return static_cast<int>(ceil(pixel_radius));
return static_cast<size_t>(ceil(pixel_radius));
}

const std::vector<Trig>& CircleTessellator::GetTrigForDivisions(
size_t divisions) {
FML_DCHECK(divisions > 0 && divisions <= MAX_DIVISIONS_);
FML_DCHECK(divisions > 0 && divisions <= kMaxDivisions);
std::vector<Trig>& trigs = trigs_[divisions];
trigs.reserve(divisions + 1);

if (trigs.empty()) {
double angle_scale = kPiOver2 / divisions;
Expand Down
7 changes: 4 additions & 3 deletions impeller/entity/geometry/circle_tessellator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,8 @@ namespace impeller {
/// @brief A structure to store the sine and cosine of an angle.
struct Trig {
/// Construct a Trig object from a given angle in radians.
Trig(Radians r) : cos(std::cos(r.radians)), sin(std::sin(r.radians)) {}
explicit Trig(Radians r)
: cos(std::cos(r.radians)), sin(std::sin(r.radians)) {}

/// Construct a Trig object from the given cosine and sine values.
Trig(double cos, double sin) : cos(cos), sin(sin) {}
Expand Down Expand Up @@ -128,9 +129,9 @@ class CircleTessellator {
/// @return The vector of (divisions + 1) trig values.
static const std::vector<Trig>& GetTrigForDivisions(size_t divisions);

static constexpr int MAX_DIVISIONS_ = 35;
static constexpr int kMaxDivisions = 35;

static std::vector<Trig> trigs_[MAX_DIVISIONS_ + 1];
static std::vector<Trig> trigs_[kMaxDivisions + 1];
};

} // namespace impeller
67 changes: 46 additions & 21 deletions impeller/entity/geometry/ellipse_geometry.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -18,20 +18,33 @@ GeometryResult EllipseGeometry::GetPositionBuffer(
const Entity& entity,
RenderPass& pass) const {
auto& host_buffer = pass.GetTransientsBuffer();
using VT = SolidFillVertexShader::PerVertexData;

VertexBufferBuilder<SolidFillVertexShader::PerVertexData> vtx_builder;

Scalar radius = radius_;
const Point& center = center_;
CircleTessellator tessellator(entity.GetTransform(), radius_);
vtx_builder.Reserve(tessellator.GetCircleVertexCount());
tessellator.GenerateCircleTriangleStrip(
[&vtx_builder](const Point& p) { //
vtx_builder.AppendVertex({.position = p});
},
center_, radius_);
size_t count = tessellator.GetCircleVertexCount();
auto vertex_buffer =
host_buffer.Emplace(count * sizeof(VT), alignof(VT),
[&tessellator, &center, radius](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
tessellator.GenerateCircleTriangleStrip(
[&vertices](const Point& p) { //
*vertices++ = {
.position = p,
};
},
center, radius);
});

return GeometryResult{
.type = PrimitiveType::kTriangleStrip,
.vertex_buffer = vtx_builder.CreateVertexBuffer(host_buffer),
.vertex_buffer =
{
.vertex_buffer = vertex_buffer,
.vertex_count = count,
.index_type = IndexType::kNone,
},
.transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()) *
entity.GetTransform(),
.prevent_overdraw = false,
Expand All @@ -46,25 +59,37 @@ GeometryResult EllipseGeometry::GetPositionUVBuffer(
const Entity& entity,
RenderPass& pass) const {
auto& host_buffer = pass.GetTransientsBuffer();

using VT = TextureFillVertexShader::PerVertexData;
auto uv_transform =
texture_coverage.GetNormalizingTransform() * effect_transform;
VertexBufferBuilder<TextureFillVertexShader::PerVertexData> vtx_builder;

Scalar radius = radius_;
const Point& center = center_;
CircleTessellator tessellator(entity.GetTransform(), radius_);
vtx_builder.Reserve(tessellator.GetCircleVertexCount());
tessellator.GenerateCircleTriangleStrip(
[&vtx_builder, &uv_transform](const Point& p) {
vtx_builder.AppendVertex({
.position = p,
.texture_coords = uv_transform * p,
});
},
center_, radius_);
size_t count = tessellator.GetCircleVertexCount();
auto vertex_buffer = host_buffer.Emplace(
count * sizeof(VT), alignof(VT),
[&tessellator, &uv_transform, &center, radius](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
tessellator.GenerateCircleTriangleStrip(
[&vertices, &uv_transform](const Point& p) { //
*vertices++ = {
.position = p,
.texture_coords = uv_transform * p,
};
},
center, radius);
});

return GeometryResult{
.type = PrimitiveType::kTriangleStrip,
.vertex_buffer = vtx_builder.CreateVertexBuffer(host_buffer),
.vertex_buffer =
{
.vertex_buffer = vertex_buffer,
.vertex_count = count,
.index_type = IndexType::kNone,
},
// .vertex_buffer = vtx_builder.CreateVertexBuffer(host_buffer),
.transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()) *
entity.GetTransform(),
.prevent_overdraw = false,
Expand Down
117 changes: 79 additions & 38 deletions impeller/entity/geometry/line_geometry.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -68,37 +68,58 @@ bool LineGeometry::ComputeCorners(Point corners[4],
GeometryResult LineGeometry::GetPositionBuffer(const ContentContext& renderer,
const Entity& entity,
RenderPass& pass) const {
auto& host_buffer = pass.GetTransientsBuffer();
using VT = SolidFillVertexShader::PerVertexData;

auto& transform = entity.GetTransform();
auto radius = ComputeHalfWidth(transform);

VertexBufferBuilder<SolidFillVertexShader::PerVertexData> vtx_builder;

size_t count;
BufferView vertex_buffer;
if (cap_ == Cap::kRound) {
const Point& p0 = p0_;
const Point& p1 = p1_;

CircleTessellator tessellator(transform, radius);
vtx_builder.Reserve(tessellator.GetCircleVertexCount());
tessellator.GenerateRoundCapLineTriangleStrip(
[&vtx_builder](const Point& p) { //
vtx_builder.AppendVertex({.position = p});
},
p0_, p1_, radius);
count = tessellator.GetCircleVertexCount();
vertex_buffer =
host_buffer.Emplace(count * sizeof(VT), alignof(VT),
[&tessellator, &p0, &p1, radius](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
tessellator.GenerateRoundCapLineTriangleStrip(
[&vertices](const Point& p) { //
*vertices++ = {
.position = p,
};
},
p0, p1, radius);
});
} else {
Point corners[4];
if (ComputeCorners(corners, transform, cap_ == Cap::kSquare)) {
vtx_builder.Reserve(4);
vtx_builder.AppendVertex({.position = corners[0]});
vtx_builder.AppendVertex({.position = corners[1]});
vtx_builder.AppendVertex({.position = corners[2]});
vtx_builder.AppendVertex({.position = corners[3]});
count = 4;
vertex_buffer = host_buffer.Emplace(
count * sizeof(VT), alignof(VT), [&corners](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
for (auto& corner : corners) {
*vertices++ = {
.position = corner,
};
}
});
} else {
return {};
}
}
if (!vtx_builder.HasVertices()) {
return {};
}

return GeometryResult{
.type = PrimitiveType::kTriangleStrip,
.vertex_buffer =
vtx_builder.CreateVertexBuffer(pass.GetTransientsBuffer()),
{
.vertex_buffer = vertex_buffer,
.vertex_count = count,
.index_type = IndexType::kNone,
},
.transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()) *
entity.GetTransform(),
.prevent_overdraw = false,
Expand All @@ -111,44 +132,64 @@ GeometryResult LineGeometry::GetPositionUVBuffer(Rect texture_coverage,
const ContentContext& renderer,
const Entity& entity,
RenderPass& pass) const {
auto& host_buffer = pass.GetTransientsBuffer();
using VT = TextureFillVertexShader::PerVertexData;

auto& transform = entity.GetTransform();
auto radius = ComputeHalfWidth(transform);

auto uv_transform =
texture_coverage.GetNormalizingTransform() * effect_transform;
VertexBufferBuilder<TextureFillVertexShader::PerVertexData> vtx_builder;

size_t count;
BufferView vertex_buffer;
if (cap_ == Cap::kRound) {
const Point& p0 = p0_;
const Point& p1 = p1_;

CircleTessellator tessellator(transform, radius);
vtx_builder.Reserve(tessellator.GetCircleVertexCount());
tessellator.GenerateRoundCapLineTriangleStrip(
[&vtx_builder, &uv_transform](const Point& p) {
vtx_builder.AppendVertex({
.position = p,
.texture_coords = uv_transform * p,
});
},
p0_, p1_, radius);
count = tessellator.GetCircleVertexCount();
vertex_buffer = host_buffer.Emplace(
count * sizeof(VT), alignof(VT),
[&tessellator, &uv_transform, &p0, &p1, radius](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
tessellator.GenerateRoundCapLineTriangleStrip(
[&vertices, &uv_transform](const Point& p) { //
*vertices++ = {
.position = p,
.texture_coords = uv_transform * p,
};
},
p0, p1, radius);
});
} else {
Point corners[4];
if (ComputeCorners(corners, transform, cap_ == Cap::kSquare)) {
vtx_builder.Reserve(4);
for (auto& corner : corners) {
vtx_builder.AppendVertex({
.position = corner,
.texture_coords = uv_transform * corner,
});
}
count = 4;
vertex_buffer =
host_buffer.Emplace(count * sizeof(VT), alignof(VT),
[&uv_transform, &corners](uint8_t* buffer) {
auto vertices = reinterpret_cast<VT*>(buffer);
for (auto& corner : corners) {
*vertices++ = {
.position = corner,
.texture_coords = uv_transform * corner,
};
}
});
} else {
return {};
}
}
if (!vtx_builder.HasVertices()) {
return {};
}

return GeometryResult{
.type = PrimitiveType::kTriangleStrip,
.vertex_buffer =
vtx_builder.CreateVertexBuffer(pass.GetTransientsBuffer()),
{
.vertex_buffer = vertex_buffer,
.vertex_count = count,
.index_type = IndexType::kNone,
},
.transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()) *
entity.GetTransform(),
.prevent_overdraw = false,
Expand Down