[gui] Remove cached arrays (#8223)

Issue: #

### Brief Summary

<!--
copilot:summary
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### <samp>🤖 Generated by Copilot at d18381f</samp>

Refactored `staging_buffer.py` to fix memory leaks and optimize array
access. Removed global caches and simplified array functions.

### Walkthrough

<!--
copilot:walkthrough
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### <samp>🤖 Generated by Copilot at d18381f</samp>

* Remove global caches for depth, vbo, indices, and transforms arrays to
avoid memory leaks and overhead
([link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L12-R27),
[link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L44),
[link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L52))
* Return arrays directly from `get_depth_ndarray`, `get_vbo_field`,
`get_indices_field`, and `get_transforms_field` functions in
`staging_buffer.py`
([link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L12-R27),
[link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L44),
[link](https://github.com/taichi-dev/taichi/pull/8223/files?diff=unified&w=0#diff-fd7dee80cc57fcef55c9bedc67a63a5aee4f20ac0375921bebec55beeb5bf928L52))

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

python/taichi/ui/canvas.py

@@ -3,7 +3,13 @@
 from taichi.lang._texture import Texture
 from .scene import SceneV2
 
-from .staging_buffer import copy_all_to_vbo, copy_all_to_vbo_particle, get_indices_field, get_vbo_field, to_rgba8
+from .staging_buffer import (
+    copy_all_to_vbo,
+    copy_all_to_vbo_particle,
+    get_indices_field_v2,
+    get_vbo_field_v2,
+    to_rgba8,
+)
 from .utils import get_field_info
 
 
@@ -97,13 +103,13 @@ def triangles(self, vertices, color=(0.5, 0.5, 0.5), indices=None, per_vertex_co
             per_vertex_color (Tuple[float]): a taichi 3D vector field, \
                 where each element indicate the RGB color of a vertex.
         """
-        vbo = get_vbo_field(vertices)
+        vbo = get_vbo_field_v2(vertices)
         has_per_vertex_color = per_vertex_color is not None
         copy_all_to_vbo(vbo, vertices, 0, 0, per_vertex_color if has_per_vertex_color else 0)
         vbo_info = get_field_info(vbo)
         indices_ndarray = None
         if indices:
-            indices_ndarray = get_indices_field(indices)
+            indices_ndarray = get_indices_field_v2(indices)
         indices_info = get_field_info(indices_ndarray)
         self.canvas.triangles(vbo_info, indices_info, has_per_vertex_color, color)
 
@@ -129,13 +135,13 @@ def lines(
             per_vertex_color (tuple[float]): a taichi 3D vector field, where \
                 each element indicate the RGB color of a vertex.
         """
-        vbo = get_vbo_field(vertices)
+        vbo = get_vbo_field_v2(vertices)
         has_per_vertex_color = per_vertex_color is not None
         copy_all_to_vbo(vbo, vertices, 0, 0, per_vertex_color if has_per_vertex_color else 0)
         vbo_info = get_field_info(vbo)
         indices_ndarray = None
         if indices:
-            indices_ndarray = get_indices_field(indices)
+            indices_ndarray = get_indices_field_v2(indices)
         indices_info = get_field_info(indices_ndarray)
         self.canvas.lines(vbo_info, indices_info, has_per_vertex_color, color, width)
 
@@ -153,7 +159,7 @@ def circles(self, centers, radius, color=(0.5, 0.5, 0.5), per_vertex_color=None,
             per_vertex_radius: a taichi float field, where \
                 each element indicates the radius of a circle.
         """
-        vbo = get_vbo_field(centers)
+        vbo = get_vbo_field_v2(centers)
         has_per_vertex_color = per_vertex_color is not None
         has_per_vertex_radius = per_vertex_radius is not None
         copy_all_to_vbo_particle(

python/taichi/ui/scene.py

@@ -11,8 +11,11 @@
     copy_all_to_vbo,
     copy_all_to_vbo_particle,
     get_indices_field,
+    get_indices_field_v2,
     get_transforms_field,
+    get_transforms_field_v2,
     get_vbo_field,
+    get_vbo_field_v2,
 )
 from .utils import check_ggui_availability, get_field_info
 
@@ -157,10 +160,10 @@ def lines(
             vertex_count = vertices.shape[0] - vertex_offset
             vertex_count -= vertex_count % 2
         has_per_vertex_color = per_vertex_color is not None
-        vbo = get_vbo_field(vertices)
+        vbo = get_vbo_field_v2(vertices)
         copy_all_to_vbo(vbo, vertices, 0, 0, per_vertex_color if has_per_vertex_color else 0)
         vbo_info = get_field_info(vbo)
-        indices_ndarray = get_indices_field(indices) if indices is not None else None
+        indices_ndarray = get_indices_field_v2(indices) if indices is not None else None
         indices_info = get_field_info(indices_ndarray)
         self.scene.lines(
             vbo_info,
@@ -235,10 +238,10 @@ def mesh(
                 index_count = vertex_count  # FIXME : Need to confirm
             else:
                 index_count = indices.shape[0]
-        vbo = get_vbo_field(vertices)
+        vbo = get_vbo_field_v2(vertices)
         copy_all_to_vbo(vbo, vertices, normals, 0, per_vertex_color if has_per_vertex_color else 0)
         vbo_info = get_field_info(vbo)
-        indices_ndarray = get_indices_field(indices) if indices is not None else None
+        indices_ndarray = get_indices_field_v2(indices) if indices is not None else None
         indices_info = get_field_info(indices_ndarray)
 
         self.scene.mesh(
@@ -336,12 +339,12 @@ def mesh_instance(
         else:
             instance_count = 1
 
-        vbo = get_vbo_field(vertices)
+        vbo = get_vbo_field_v2(vertices)
         copy_all_to_vbo(vbo, vertices, normals, 0, per_vertex_color if has_per_vertex_color else 0)
         vbo_info = get_field_info(vbo)
-        indices_ndarray = get_indices_field(indices) if indices else None
+        indices_ndarray = get_indices_field_v2(indices) if indices else None
         indices_info = get_field_info(indices_ndarray)
-        transforms_ndarray = get_transforms_field(transforms) if transforms else None
+        transforms_ndarray = get_transforms_field_v2(transforms) if transforms else None
         transform_info = get_field_info(transforms_ndarray)
         self.scene.mesh_instance(
             vbo_info,
@@ -392,7 +395,7 @@ def particles(
         if index_count is None:
             index_count = centers.shape[0]
             # per_vertex_radius_vec3[i] = Vector([per_vertex_radius[i], 0., 0.])
-        vbo = get_vbo_field(centers)
+        vbo = get_vbo_field_v2(centers)
         copy_all_to_vbo_particle(
             vbo,
             centers,

python/taichi/ui/staging_buffer.py

@@ -37,6 +37,17 @@ def get_vbo_field(vertices):
     return vbo_field_cache[vertices]
 
 
+def get_vbo_field_v2(vertices):
+    N = vertices.shape[0]
+    pos = 3
+    normal = 3
+    tex_coord = 2
+    color = 4
+    vertex_stride = pos + normal + tex_coord + color
+    vbo = np.ndarray((N, vertex_stride), dtype=np.float32)
+    return vbo
+
+
 def get_indices_field(indices):
     if isinstance(indices, np.ndarray):
         return indices
@@ -45,6 +56,13 @@ def get_indices_field(indices):
     return indices_arr
 
 
+def get_indices_field_v2(indices):
+    if isinstance(indices, np.ndarray):
+        return indices
+    indices_arr = indices.to_numpy()
+    return indices_arr
+
+
 def get_transforms_field(transforms):
     if isinstance(transforms, np.ndarray):
         return transforms
@@ -53,6 +71,13 @@ def get_transforms_field(transforms):
     return transforms_arr
 
 
+def get_transforms_field_v2(transforms):
+    if isinstance(transforms, np.ndarray):
+        return transforms
+    transforms_arr = transforms.to_numpy()
+    return transforms_arr
+
+
 @kernel
 def copy_all_to_vbo(
     vbo: ndarray_type(element_dim=1),