Struct Tessellator

Source

pub struct Tessellator { /* private fields */ }

Expand description

Turns paths into GPU-ready triangle meshes.

The tessellator owns the scratch buffers it needs, so filling a chart with many series does not allocate once per shape: the buffers are reused across calls and only grow when a larger shape shows up.

A tessellator is not thread-safe; each renderer owns one.

Implementations§

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impl Tessellator

Inherent implementation of Tessellator.

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pub fn new() -> Self

Returns a tessellator with the default flattening tolerance.

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pub fn with_tolerance(tolerance: f64) -> Self

Returns a tessellator with the given flattening tolerance, in pixels.

A smaller tolerance produces smoother curves at the cost of more vertices.

§Arguments

f64 - A 64-bit float (f64).

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pub fn tolerance(&self) -> f64

Returns the flattening tolerance, in pixels.

§Returns

f64 - A 64-bit float.

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pub fn flatten(&mut self, path: &Path) -> &FlatPath

Flattens the path into contours and returns them.

The returned reference borrows the tessellator’s scratch storage and stays valid until the next call to Tessellator::flatten.

§Arguments

&Path - Shared reference to a Path.

§Returns

&FlatPath - A FlatPath value.

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pub fn fill(&mut self, path: &Path, color: u32) -> SolidMesh

Triangulates the path and returns the resulting mesh.

The path is filled according to its FillRule. Holes are detected automatically: a contour nested inside another contour with the opposite winding direction is treated as a hole, which is what makes a doughnut chart’s inner ring disappear.

§Arguments

&Path - Shared reference to a Path.
u32 - A 32-bit unsigned integer (u32).

§Returns

SolidMesh - A SolidMesh value.

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pub fn fill_flattened( &mut self, path: &Path, color: u32, rule: FillRule, ) -> SolidMesh

Triangulates the path and returns the resulting mesh, using the given fill rule.

§Arguments

&Path - Shared reference to a Path.
u32 - A 32-bit unsigned integer (u32).
FillRule - A FillRule parameter.

§Returns

SolidMesh - A SolidMesh value.

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pub fn fill_contours( &mut self, contours: &[Contour], color: u32, rule: FillRule, ) -> SolidMesh

Triangulates a set of contours and returns the resulting mesh.

§Arguments

&[Contour] - Shared reference to a [Contour].
u32 - A 32-bit unsigned integer (u32).
FillRule - A FillRule parameter.

§Returns

SolidMesh - A SolidMesh value.

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pub fn fill_strip( &mut self, points: &[Point], baseline: f32, color: u32, ) -> SolidMesh

Builds a triangle strip for the region between a polyline and a straight baseline.

This is the hot path for area charts: the shape is a strip by construction, so it needs no triangulation at all, and the whole series becomes a single indexed draw call.

points are the polyline vertices in order; baseline is the vertical coordinate the area is closed against.

§Arguments

&[Point] - Shared reference to a [Point].
f32 - A 32-bit float (f32).
u32 - A 32-bit unsigned integer (u32).

§Returns

SolidMesh - A SolidMesh value.

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pub fn stroke( &mut self, path: &Path, style: &StrokeStyle, color: u32, ) -> SolidMesh

Expands the path into stroke geometry and returns the mesh.

Every segment becomes a quad, and every join becomes a wedge, so the whole stroke is a single indexed draw call regardless of how many segments it has.