addedf a method to generate parameters for ri.Polygon from PrimData useful for renderman demos

Author: jmacey

src/ncca/ngl/__init__.py

@@ -40,7 +40,18 @@
 from .text import Text
 from .texture import Texture
 from .transform import Transform, TransformRotationOrder
-from .util import PerspMode, calc_normal, clamp, frustum, lerp, look_at, ortho, perspective, renderman_look_at
+from .util import (
+    PerspMode,
+    calc_normal,
+    clamp,
+    frustum,
+    lerp,
+    look_at,
+    ortho,
+    perspective,
+    prim_data_to_ri_points_polygons,
+    renderman_look_at,
+)
 from .vao_factory import VAOFactory, VAOType
 from .vec2 import Vec2
 from .vec2_array import Vec2Array
@@ -111,4 +122,5 @@
     PySideEventHandlingMixin,
     PerspMode,
     renderman_look_at,
+    prim_data_to_ri_points_polygons,
 ]

src/ncca/ngl/util.py

@@ -6,6 +6,8 @@
 import enum
 import math
 
+import numpy as np
+
 from .mat4 import Mat4
 
 
@@ -214,3 +216,53 @@ def renderman_look_at(eye, look, up):
     result.m[3][2] = -eye.dot(n)
 
     return result
+
+
+def prim_data_to_ri_points_polygons(triangles: np.ndarray):
+    """
+    Convert a packed numpy array of triangles to RenderMan PointsPolygons format.
+    This is designed to work with the PrimData class outputs.
+    Parameters
+    ----------
+    triangles : np.ndarray
+        Array of shape (n_vertices, 8) where each row is: x, y, z, nx, ny, nz, u, v
+        n_vertices must be divisible by 3 (since we have triangles)
+
+    Returns
+    -------
+    tuple
+        (nvertices, vertices, parameterlist)
+        - nvertices: list of vertex counts per polygon (all 3 for triangles)
+        - vertices: flat list of vertex indices
+        - parameterlist: dict with 'P', 'N', 'st' arrays for RenderMan
+    """
+    # Ensure it's a 2D array
+    if triangles.ndim == 1:
+        # If completely flat, reshape to (n_verts, 8)
+        if len(triangles) % 8 != 0:
+            raise ValueError("1D array length must be divisible by 8")
+        triangles = triangles.reshape(-1, 8)
+
+    n_verts = triangles.shape[0]
+    if n_verts % 3 != 0:
+        raise ValueError("Number of vertices must be divisible by 3")
+
+    n_triangles = n_verts // 3
+
+    # Extract components from each row
+    positions = triangles[:, 0:3]  # (n_verts, 3) - x, y, z
+    normals = triangles[:, 3:6]  # (n_verts, 3) - nx, ny, nz
+    uvs = triangles[:, 6:8]  # (n_verts, 2) - u, v
+
+    # RenderMan PointsPolygons format
+    nvertices = [3] * n_triangles  # Each polygon has 3 vertices
+    vertices = list(range(n_verts))  # Sequential vertex indices
+
+    # Parameter list - flatten to 1D arrays as RenderMan expects
+    parameterlist = {
+        "P": positions.flatten().tolist(),  # Position
+        "N": normals.flatten().tolist(),  # Normals
+        "st": uvs.flatten().tolist(),  # Texture coordinates
+    }
+
+    return nvertices, vertices, parameterlist

test_all.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env zsh
 
-uv run pytest
-uv run pytest -m opengl
-uv run pytest -m webgpu
-uv run pytest -m qt
+set -euo pipefail
+uv run pytest || exit 1
+uv run pytest -m opengl || exit 1
+uv run pytest -m webgpu || exit 1
+uv run pytest -m qt || exit 1

tests/test_util.py

@@ -1,6 +1,19 @@
+import numpy as np
 import pytest
 
-from ncca.ngl import Mat4, PerspMode, Vec3, calc_normal, clamp, frustum, lerp, look_at, ortho, perspective
+from ncca.ngl import (
+    Mat4,
+    PerspMode,
+    Vec3,
+    calc_normal,
+    clamp,
+    frustum,
+    lerp,
+    look_at,
+    ortho,
+    perspective,
+    prim_data_to_ri_points_polygons,
+)
 
 
 def test_clamp():
@@ -101,3 +114,23 @@ def test_frustum():
         ],
         abs=1e-3,
     )
+
+
+def test_prim_data_to_ri_points_polygons():
+    # Create example triangle data
+    triangles = np.array(
+        [
+            # Triangle 1: 3 vertices, each with x,y,z,nx,ny,nz,u,v
+            [[0, 0, 0, 0, 0, 1, 0, 0], [1, 0, 0, 0, 0, 1, 1, 0], [0, 1, 0, 0, 0, 1, 0, 1]],
+            # Triangle 2
+            [[1, 0, 0, 0, 0, 1, 1, 0], [1, 1, 0, 0, 0, 1, 1, 1], [0, 1, 0, 0, 0, 1, 0, 1]],
+        ],
+        dtype=np.float32,
+    ).flatten()
+
+    nvertices, vertices, parameterlist = prim_data_to_ri_points_polygons(triangles)
+    assert nvertices == [3, 3]
+    assert vertices == [0, 1, 2, 3, 4, 5]
+    assert parameterlist.get("P")
+    assert parameterlist.get("N")
+    assert parameterlist.get("st")

tests/test_vec3.py

@@ -5,7 +5,7 @@
 import numpy as np
 import pytest
 
-from ncca.ngl import Mat3, Vec3, Vec2, Vec4
+from ncca.ngl import Mat3, Vec2, Vec3, Vec4
 
 
 def test_properties():