GPv3: Rendering compound shapes #114071

New Issue

Falk David · 2023-10-23T19:25:45+02:00

Falk David commented

2023-10-23 19:25:45 +02:00

Design

We can represent compund shape by having a shape_id attribute on the Curve domain.
By default, every curve would have its own shape_id, e.g. 0, 1, 2, 3, etc.

When two curves have the same shape_id they are considered to be part of the same shape.

Implementation

Add an operator to put the selected curves into the same shape (give it the same shape_id attribute).
Rewrite the Drawing::triangles() to compute the triangles for every shape rather than curve (if there exists a shape_id attribute).
- Instead of iteration over all curves, compute an IndexMask of curves for every shape. Then compute the triangles of every shape by building a 2d array of points for each shape and calling BLI_polyfill_calc_arena on that.
Make sure the grease_pencil_geom_batch_ensure function still works with the change above.

## Design We can represent compund shape by having a `shape_id` attribute on the `Curve` domain. By default, every curve would have its own `shape_id`, e.g. `0`, `1`, `2`, `3`, etc. When two curves have the same `shape_id` they are considered to be part of the same shape. ## Implementation - [ ] Add an operator to put the selected curves into the same shape (give it the same `shape_id` attribute). - [ ] Rewrite the `Drawing::triangles()` to compute the triangles for every shape rather than curve (if there exists a `shape_id` attribute). * Instead of iteration over all curves, compute an `IndexMask` of curves for every shape. Then compute the triangles of every shape by building a 2d array of points for each shape and calling `BLI_polyfill_calc_arena` on that. - [ ] Make sure the `grease_pencil_geom_batch_ensure` function still works with the change above.

Falk David added the

Type

To Do

label 2023-10-23 19:25:45 +02:00

Falk David added this to the Grease Pencil project 2023-10-23 19:25:47 +02:00

Falk David changed title from ~~GPv3: Compound Shape Support (for geometric holes)~~ to GPv3: Rendering compound shapes

2023-10-24 11:06:22 +02:00

Falk David commented

2023-10-31 15:41:26 +01:00

During the conference I took some notes on how we can use the delauny triangulation algorithm in Blender for this:

How to find a good fitting plane for a set of 3d coordinates:

float3 plane_n;
normal_poly_v3(plane_n, points_3d, points_3d.size());
float3 plane_o = arithmetic_mean(points_3d);

How to project all the coordinates to that plane:

proj_point = point - math::scale(plane_n, math::dot(plane_n, point - plane_o));

The input meshintersect::CDT_input<double> takes all the 2D points in the verts array. Then the face array contains a vector of indices into the verts array for each element.

Then call the delauney algorithm like this:

meshintersect::CDT_result<double> result = delaunay_2d_calc(input, CDT_INSIDE_WITH_HOLES);

During the conference I took some notes on how we can use the delauny triangulation algorithm in Blender for this: How to find a good fitting plane for a set of 3d coordinates: ``` float3 plane_n; normal_poly_v3(plane_n, points_3d, points_3d.size()); float3 plane_o = arithmetic_mean(points_3d); ``` How to project all the coordinates to that plane: ``` proj_point = point - math::scale(plane_n, math::dot(plane_n, point - plane_o)); ``` The input `meshintersect::CDT_input<double>` takes all the 2D points in the `verts` array. Then the `face` array contains a vector of indices into the `verts` array for each element. Then call the delauney algorithm like this: ``` meshintersect::CDT_result<double> result = delaunay_2d_calc(input, CDT_INSIDE_WITH_HOLES); ```

casey-bianco-davis self-assigned this 2023-12-14 18:17:50 +01:00

casey-bianco-davis referenced a pull request that will close this issue

2024-01-02 00:21:15 +01:00

WIP: GPv3: Compound shapes rendering and operators #116698

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

GPv3: Rendering compound shapes #114071

Design

Implementation