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Don't start subdividing active edges until we're sure an entire B-quad 

will be emitted.

Otherwise it messes up the parity.

Fixes the bottom curve of the lowercase "p" in Open Sans when rendered
with Loop-Blinn.
This commit is contained in:
Patrick Walton 2017-09-29 13:25:19 -07:00
parent 08b9afdca9
commit 613bc7c29d
1 changed files with 21 additions and 16 deletions
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37
partitioner/src/partitioner.rs
View File

@ -529,12 +529,17 @@ impl<'a> Partitioner<'a> {
return emission_result
}
if !self.should_subdivide_active_edge_at(upper_active_edge_index, right_x) ||
!self.should_subdivide_active_edge_at(lower_active_edge_index, right_x) {
return emission_result
}
let upper_curve = self.subdivide_active_edge_at(upper_active_edge_index,
right_x,
SubdivisionType::Upper);
for active_edge_index in (upper_active_edge_index + 1)..lower_active_edge_index {
if self.subdivide_active_edge_at(active_edge_index, right_x, SubdivisionType::Inside)
.is_some() {
if self.should_subdivide_active_edge_at(active_edge_index, right_x) {
self.subdivide_active_edge_at(active_edge_index, right_x, SubdivisionType::Inside);
self.active_edges[active_edge_index as usize].toggle_parity();
}
}
@ -542,13 +547,11 @@ impl<'a> Partitioner<'a> {
right_x,
SubdivisionType::Lower);
if let (Some(upper_curve), Some(lower_curve)) = (upper_curve, lower_curve) {
self.emit_b_quads(upper_active_edge_index,
lower_active_edge_index,
&upper_curve,
&lower_curve,
0);
}
self.emit_b_quads(upper_active_edge_index,
lower_active_edge_index,
&upper_curve,
&lower_curve,
0);
emission_result
}
@ -1022,18 +1025,20 @@ impl<'a> Partitioner<'a> {
}
}
fn should_subdivide_active_edge_at(&self, active_edge_index: u32, x: f32) -> bool {
let left_curve_left = self.active_edges[active_edge_index as usize].left_vertex_index;
let left_point_position = self.b_vertex_positions[left_curve_left as usize];
x - left_point_position.x >= f32::approx_epsilon()
}
/// Does *not* toggle parity. You must do this after calling this function.
fn subdivide_active_edge_at(&mut self,
active_edge_index: u32,
x: f32,
subdivision_type: SubdivisionType)
-> Option<SubdividedActiveEdge> {
-> SubdividedActiveEdge {
let left_curve_left = self.active_edges[active_edge_index as usize].left_vertex_index;
let left_point_position = self.b_vertex_positions[left_curve_left as usize];
if x - left_point_position.x < f32::approx_epsilon() {
// Too thin to make a difference. Forget it.
return None
}
let t = self.solve_active_edge_t_for_x(x, &self.active_edges[active_edge_index as usize]);
@ -1091,11 +1096,11 @@ impl<'a> Partitioner<'a> {
}
}
Some(SubdividedActiveEdge {
SubdividedActiveEdge {
left_curve_left: left_curve_left,
left_curve_control_point: left_curve_control_point_vertex_index,
middle_point: active_edge.left_vertex_index,
})
}
}
fn prev_endpoint_of(&self, endpoint_index: u32) -> u32 {