Cosmetic tweaks to query_gltf_primitives (bevyengine#16102)

# Objective

This example is really confusing to look at and tell at a glance whether
it's broken or not.

It's displaying a strange shape -- a cube with two vertices stretched in
a couple dimensions at an odd angle, and doing its vertex position
modification in a way where the intent isn't obvious.

## Solution

- Change the gltf geometry so that the object is a recognizable regular
shape
- Change the vertex modification so that the entire cube top is being
"lifted" from the cube
- Adjust colors, lighting, and camera location so we can see what's
going on
- Also remove some irrelevant shadow and environment map setup

## Before


![Image](https://github.com/user-attachments/assets/e5dd5075-0480-49d4-b1ed-cf1fe6106f3c)

## After

<img width="1280" alt="image"
src="https://github.com/user-attachments/assets/59cab60d-efbc-47c3-8688-e4544b462421">

Author: rparrett

assets/models/GltfPrimitives/gltf_primitives.glb

@@ -3,16 +3,10 @@
 
 use std::f32::consts::PI;
 
-use bevy::{
-    gltf::GltfMaterialName,
-    pbr::{CascadeShadowConfigBuilder, DirectionalLightShadowMap},
-    prelude::*,
-    render::mesh::VertexAttributeValues,
-};
+use bevy::{gltf::GltfMaterialName, prelude::*, render::mesh::VertexAttributeValues};
 
 fn main() {
     App::new()
-        .insert_resource(DirectionalLightShadowMap { size: 4096 })
         .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
         .add_systems(Update, find_top_material_and_mesh)
@@ -36,20 +30,22 @@ fn find_top_material_and_mesh(
                 if let Color::Hsla(ref mut hsla) = material.base_color {
                     *hsla = hsla.rotate_hue(time.delta_secs() * 100.0);
                 } else {
-                    material.base_color = Color::from(Hsla::hsl(0.0, 0.8, 0.5));
+                    material.base_color = Color::from(Hsla::hsl(0.0, 0.9, 0.7));
                 }
             }
 
             if let Some(mesh) = meshes.get_mut(mesh_handle) {
                 if let Some(VertexAttributeValues::Float32x3(positions)) =
                     mesh.attribute_mut(Mesh::ATTRIBUTE_POSITION)
                 {
-                    positions[0] = (
-                        ops::sin(2.0 * PI * time.elapsed_secs()),
-                        positions[0][1],
-                        positions[0][2],
-                    )
-                        .into();
+                    for position in positions {
+                        *position = (
+                            position[0],
+                            1.5 + 0.5 * ops::sin(time.elapsed_secs() / 2.0),
+                            position[2],
+                        )
+                            .into();
+                    }
                 }
             }
         }
@@ -59,38 +55,15 @@ fn find_top_material_and_mesh(
 fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands.spawn((
         Camera3d::default(),
-        Transform::from_xyz(0.6, 1.6, 11.3).looking_at(Vec3::new(0.0, 0.0, 3.0), Vec3::Y),
-        EnvironmentMapLight {
-            diffuse_map: asset_server.load("environment_maps/pisa_diffuse_rgb9e5_zstd.ktx2"),
-            specular_map: asset_server.load("environment_maps/pisa_specular_rgb9e5_zstd.ktx2"),
-            intensity: 500.0,
-            rotation: Quat::IDENTITY,
-        },
+        Transform::from_xyz(4.0, 4.0, 12.0).looking_at(Vec3::new(0.0, 0.0, 0.5), Vec3::Y),
     ));
 
     commands.spawn((
-        DirectionalLight {
-            shadows_enabled: true,
-            ..default()
-        },
-        // This is a relatively small scene, so use tighter shadow
-        // cascade bounds than the default for better quality.
-        // We also adjusted the shadow map to be larger since we're
-        // only using a single cascade.
-        CascadeShadowConfigBuilder {
-            num_cascades: 1,
-            maximum_distance: 1.6,
-            ..default()
-        }
-        .build(),
-    ));
-    commands.spawn((
-        SceneRoot(asset_server.load(
-            GltfAssetLabel::Scene(0).from_asset("models/GltfPrimitives/gltf_primitives.glb"),
-        )),
-        Transform {
-            rotation: Quat::from_rotation_y(-90.0 / 180.0 * PI),
-            ..default()
-        },
+        Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, 1.0, -PI / 4.)),
+        DirectionalLight::default(),
     ));
+
+    commands.spawn(SceneRoot(asset_server.load(
+        GltfAssetLabel::Scene(0).from_asset("models/GltfPrimitives/gltf_primitives.glb"),
+    )));
 }