CURA-13250 chamfered tree base by wawanbreton · Pull Request #2346 · Ultimaker/CuraEngine

Erwan MATHIEU (wawanbreton) · 2026-07-14T10:33:33Z

This PR's main goal is to implement the chamfered base for the support, both tree and normal. The base makes the bottom of the support much sturdier and also improves adhesion to the buildplate, so it is now possible to use higher supports, or tree supports with less trunks.

In addition to that, it contains a few other significant changes:

The support walls are no more generated using Arachne, but a naive insetting operation instead. Since we don't really care about dimentional accuracy nor fine details in the support, using a naive algorithm helps reducing the slicing time a lot when using especially tree support that generate a lot of tiny tips.
Fix in the skirt generation: so far, the skirt generation was using an approximation of the convex hull of the models on the buildplate. In some situations this process would generate invalid self-intersecting polygons, so it is now replaced by the actual convex hull calculation, which gives a correct result and also happens to be way faster. This is a very visible behavior change though, because the skirt is no more rounded as it used to be, however it has more straight lines which help for adhesion while priming, and also it is now always composed of a single line enclosing the whole print, no more multiple pieces attracted to each other.
introduction of CuraEngineViz: we now have a dedicated tool to visualize the internal data of the engine in real-time. The engine contains the interface part that sends the raw data to the visualizer, which is of course disabled by default and can be enabled with a -o "with_curaviz=True" at conan install time

Requires Ultimaker/Cura#21714

CURA-13250 The approximateConvexHull function relied on doing a very large outer offset, then reverting it back, to get a convex-hull like rounded polygon. However, this method seemed to produce self-intersecting polygons in some cases, which propagated to doing non-closed skirt lines. We now use the actual convex hull calculation, which also happens to be much faster. In practice, that means the following changes: * Skirt is less rounded, which should actually be preferable because it uses less material and should help adhesion by doing more long straight lines * Objects far from each other (usually prime tower) are now included in the same convex skirt, where they could be disjoint with a weird shape before

CURA-13250

CURA-13183

CURA-13250

github-actions · 2026-07-14T10:46:12Z

Test Results

31 tests 31 ✅ 5s ⏱️
1 suites 0 💤
1 files 0 ❌

Results for commit c9fc367.

♻️ This comment has been updated with latest results.

Erwan MATHIEU (wawanbreton)

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'C++ Benchmark'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.50.

Benchmark suite	Current: `1c13d54`	Previous: `5a53fc2`	Ratio
`SimplifyTestFixture/simplify_slot_noplugin`	`4.2190767982101764` ns/iter	`2.5989174745839803` ns/iter	`1.62`

This comment was automatically generated by workflow using github-action-benchmark.

CC: Jelle Spijker (@jellespijker) Erwan MATHIEU (@wawanbreton) Casper Lamboo (@casperlamboo) HellAholic

CURA-13250

Casper Lamboo (casperlamboo)

I don;t fully understand the need of changing x.getInfillArea() to x.outline_

Casper Lamboo (casperlamboo) · 2026-07-16T06:54:21Z

    return index.value;
 }

+constexpr LayerIndex distance(const LayerIndex& lhs, const LayerIndex& rhs)


This function feels a bit weird to me since

distance in this case can be negative

distance returns an Index type
A better name for this function would be layerDelta, layersBetween or layersTo in my opinion.

Well, it has to be called distance to match the standard std::distance so that we can use LayerIndex directly in a parallel_for loop.
Maybe a comment would be helpful ?

Casper Lamboo (casperlamboo) · 2026-07-16T08:30:23Z

+    /*!
+     * Generates a series of outsetting walls around a given shape
+     * @param shape The shape to be wrapped
+     * @param width The maximum width to be reached, actual result may be thinner but never larger
+     * @param line_width The line width to be used to print each outset line
+     * @return The generated outset lines and the actual width of the outermost contour
+     */
+    static InsetOutset generateOutset(const Shape& shape, const coord_t width, const coord_t line_width);
+
+    /*!
+     * Generates a series of insetting walls inside a given shape
+     * @param shape The shape to be filled
+     * @param width The maximum width to be reached, actual result may be thinner but never larger
+     * @param line_width The line width to be used to print each inset line
+     * @return The generated inset lines and the actual width of the innermost contour
+     */
+    static InsetOutset generateInset(const Shape& shape, const coord_t width, const coord_t line_width);


Can't this be achieved using a single function where width can be either negative or positive, same for generateInsetOutset? It would also be more inline with the offset function where the `offset parameter can be positive or negative.

That is actually what is done under the hood. There is a private generateInsetOutset method that is called by both. As an external API I find it nicer to have two explicit functions rather than giving an extra argument.

Casper Lamboo (casperlamboo) · 2026-07-16T09:33:35Z

    Shape covered_area = storage_.getLayerOutlines(
        0,
        /*include_support*/ true,
-        /*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT);
+        /*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT,
+        /*external_polys_only*/ false,
+        /*extruder_nr*/ -1,
+        /*include_models*/ true,
+        /*include_support_base*/ false);


I think we should be using named variables for consistency.

Suggested change

Shape covered_area = storage_.getLayerOutlines(

0,

/*include_support*/ true,

/*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT);

/*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT,

/*external_polys_only*/ false,

/*extruder_nr*/ -1,

/*include_models*/ true,

/*include_support_base*/ false);

constexpr LayerIndex layer_nr = 0;

constexpr bool include_support = true;

const bool include_prime_tower = adhesion_type_ == EPlatformAdhesion::SKIRT;

constexpr coord_t extruder_nr = -1;

constexpr bool include_models = true;

constexpr bool include_support_base = false;

Shape covered_area = storage_.getLayerOutlines(

layer_nr,

include_support,

include_prime_tower,

external_polys_only,

extruder_nr,

include_models,

include_support_base

);

Casper Lamboo (casperlamboo) · 2026-07-16T12:56:20Z

+                }),
+            base_inset.end());
+
+        if (base_inset.length() > 0)


Suggested change

if (base_inset.length() > 0)

if (! base_inset.empty())

In this case, length() gives the contained lines total length, so it does check that the list is not empty, and also that it contains non-empty polylines. Probably a bit redundant, but slightly safer. I think I actually moved this check from somewhere else.

Co-authored-by: Casper Lamboo <casperlamboo@gmail.com>

CURA-13250

Erwan MATHIEU (wawanbreton) · 2026-07-16T15:11:43Z

I don;t fully understand the need of changing x.getInfillArea() to x.outline_

SupportInfillPart was a class with only public variables. Now it is a struct, still with the same elements. I actually don't see a need for the getInfillArea method, since it just returns the outline_ which is publicly accessible anyway. It was confusing that you could get the same element by 2 different means IMHO.

Erwan MATHIEU (wawanbreton) and others added 26 commits July 7, 2026 10:44

Implement support outside base

36f8ba3

CURA-13185

Apply clang-format

7826e71

Handle skirt and raft with support base

fc04db9

CURA-13185

Handle inside support base

649111a

CURA-13185

Multi-thread base support generation

7b67615

CURA-13185

Apply clang-format

1dc855c

Don't use arachne to generate the support walls

e83002f

CURA-13183

Add missing header

563cf57

CURA-13183

Fix non-arachne support walls generation

a843649

CURA-13226

Do not generate support brim within support generation

b3cd342

CURA-13250

Basic CuraViz POC

a1e2ea8

Send build plate info before anything else

bd4c5b8

Add method to send a shape/list of shapes

955f8dc

CURA-13250

Generate support first layer using brim generation

653629a

CURA-13250

Handle support base first layer within brim

b8c0735

CURA-13250

Apply clang-format

d5eb23e

Fix support base with raft

739276e

CURA-13250

Fix possible crash with null base height

4643ac0

CURA-13250

Handle extra support base settings

1b2f3eb

CURA-13250

Allow generation of support inside base with infill

45601f4

CURA-13183

Fix inner base with infill

4fa902b

CURA-13250

Fix outer base generation on first layer

30761f8

CURA-13250

Fix outer base possibly overlapping support interface

e437e7f

CURA-13250

Apply clang-format

47a21c9

Polish debug visualization code

1c13d54

CURA-13250

Erwan MATHIEU (wawanbreton) mentioned this pull request Jul 14, 2026

CURA-13250 Define settings for chamfered support base Ultimaker/Cura#21714

Open

Erwan MATHIEU (wawanbreton) marked this pull request as draft July 14, 2026 10:34

Erwan MATHIEU (wawanbreton) commented Jul 14, 2026

View reviewed changes

Erwan MATHIEU (wawanbreton) and others added 2 commits July 14, 2026 13:47

Polish code and add documentation

29e32f5

CURA-13250

Apply clang-format

84e10e8

Erwan MATHIEU (wawanbreton) marked this pull request as ready for review July 14, 2026 11:49

Casper Lamboo (casperlamboo) reviewed Jul 16, 2026

View reviewed changes

Erwan MATHIEU (wawanbreton) and others added 3 commits July 16, 2026 17:02

Apply suggestions from code review

aab738d

Co-authored-by: Casper Lamboo <casperlamboo@gmail.com>

Apply code review suggestion

71b97b7

CURA-13250

Remove zombie method definition

c9fc367

CURA-13250

-    Shape covered_area = storage_.getLayerOutlines(
-,
-        /*include_support*/ true,
-        /*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT);
-        /*include_prime_tower*/ adhesion_type_ == EPlatformAdhesion::SKIRT,
-        /*external_polys_only*/ false,
-        /*extruder_nr*/ -1,
-        /*include_models*/ true,
-        /*include_support_base*/ false);
+    constexpr LayerIndex layer_nr = 0;
+    constexpr bool include_support = true;
+    const bool include_prime_tower = adhesion_type_ == EPlatformAdhesion::SKIRT;
+    constexpr coord_t extruder_nr = -1;
+    constexpr bool include_models = true;
+    constexpr bool include_support_base = false;
+    Shape covered_area = storage_.getLayerOutlines(
+        layer_nr,
+        include_support,
+        include_prime_tower,
+        external_polys_only,
+        extruder_nr,
+        include_models,
+        include_support_base
+    );

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Erwan MATHIEU (wawanbreton) commented Jul 14, 2026

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⚠️ Performance Alert ⚠️

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