Add a Gaussian Splat and octomap rendering sample (#1247)

* Add a complex sample showing how to do a simplistic tool that shows a Voxel Point Cloud map using Octomap.  Also demonstrates how to use ImGUI in a project with added functionality and positioning of rendered assets.

* Add Gaussian splat rendering and GLTF support to octomap sample

Extends the octomap sample with three view modes: Octomap, GLTF Regular, and GLTF Splats. Implements splat rendering pipeline with per-instance attributes and premultiplied alpha blending. Adds GLTF mesh rendering with vertex color support. Includes new shader files for splat geometry and fragment evaluation. Updates camera to FirstPerson type for WASD movement. Fixes cube winding order and improves command buffer recording. Adds proper license headers to all new and modified files.

* Reformat and reorganize includes in octomap sample

Standardizes code formatting with consistent indentation and brace style. Reorders includes alphabetically with core utilities first. Consolidates constructor initializer list to single line. Adjusts spacing and alignment throughout for consistency.

* Add explicit submodule update step to all workflow jobs

Ensures submodules are fully initialized and updated in each job by adding explicit `git submodule update --init --recursive` command after checkout, complementing the existing `submodules: "recursive"` checkout option.

* Fix indentation in .gitmodules for octomap submodule

Replaces spaces with tabs to maintain consistent formatting throughout the .gitmodules file.

* Add octomap file for complex render sample

* Restrict render_octomap sample to platforms with GLFW support

* Force Windows to build library as static to hopefully fix CI.

* Implement update_overlay method for render_octomap sample

Adds update_overlay method override that delegates to custom ImGUI implementation in render() function and executes additional UI callbacks when provided.

* Fix header guard naming and exclude octomap submodule from CI checks

Renames header guards in ImGUIUtil.h from ORB_SLAM3_IMGUI_H to IMGUI_UTIL_H to match the actual file name. Excludes samples/complex/render_octomap/octomap directory from CI workflow file checks.

* Add braces to single-statement conditionals and replace C-style casts with static_cast

Improves code style consistency by adding braces to all single-statement if blocks. Replaces C-style casts with appropriate static_cast and reinterpret_cast. Filters out third_party/glfw warnings from clang-tidy output in CI workflow.

* Fix indentation in render_octomap sample

Replaces leading spaces with tabs to maintain consistent formatting throughout the file.

* Refactor ImGUI input handling to use platform-agnostic framework events

Replaces GLFW-specific key handling with framework's KeyCode enum for platform-agnostic input. Renames handleKey to handle_key_event to match framework naming conventions. Updates modifier key state tracking to use ImGui's key state. Removes GLFW dependency and platform-specific conditionals from ImGUI implementation. Enables render_octomap sample on all platforms including Android, iOS, and Direct-to-Display.

* Update copyright year to 2026

Updates copyright headers across framework components and shaders from 2025 to 2026.

* Update copyright years in project files

Updated copyright headers across various project files to reflect the year 2026. This ensures consistency and compliance with licensing requirements.

* Update Gaussian splatting implementation to follow KHR_gaussian_splatting spec

Moves Gaussian splatting attributes from extension object to primitive attributes using KHR_gaussian_splatting namespace. Updates attribute parsing to check KHR_gaussian_splatting:ROTATION, SCALE, OPACITY, and SH_DEGREE_0_COEF_0 in primitive attributes first, with fallback to old draft extension properties and COLOR_0. Simplifies extension parsing logic and removes nested property structures. Updates code examples in tutorial documentation to reflect new attribute structure.

* clang-format

* fix the compile

* Update to latest KHR and use sample map.

* Update to show we do not need to use MoltenVK for rendering.

* clang-format fixes.

* Fix windows having 32bit limit on a static lib.

* Allow imgui to update with keyboard nav.  fix name.size() >= 5 and add in built spv files so platforms that oddly don't auto build will work.

* Fix for keyboard navigation and numpad look handling

* clang-format

* address Sascha's nit on KHR_gaussian_splatting extension name  (Diverges from what we do in GLTF_Loader in the framework, but it's a good idea).

* Expand README for Octomap sample to include usage, controls, rendering modes, and key implementation details.

* I forgot to add in the complex samples section to nav.adoc along with the rest of the documentation.

* address comment.

* Address feedback.

* Update Gaussian Splat documentation and implementation to include additional attributes and clarifications

- Add `:stem:` attribute for mathematical expressions in the documentation.
- Clarify SPZ compression details and the use of PLY as raw data storage.
- Adjust JSON examples to include new attributes (`antialiased` and `shDegree`).
- Switch to `SplatInstance` struct for interleaved data storage in the code.
- Expand explanations around projection math, blending, and premultiplied alpha use.
- Highlight mandatory depth sorting for correct rendering.

* Update to better describe how to add custom UI textures.

* clang-format

* Address Andreas' comments.  Thanks!  keep them coming!

* clang-format.

* try to resolve clang-format

* Remove ImGui from the complex render_octomap sample inlcuding the instruction.

Move to the Framework imgui

Address rest of Andreas' comments.

* Address Andreas' latest comments.

Author: gpx1000

.github/workflows/build.yml

@@ -24,6 +24,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
       - if: ${{ matrix.platform == 'ubuntu' }}
         name: Install RandR headers
         run: |
@@ -68,6 +70,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
 
       - if: ${{ matrix.platform == 'ubuntu' }}
         name: Install RandR headers
@@ -97,6 +101,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
       - name: ccache
         uses: hendrikmuhs/ccache-action@v1.2.9
         with:
@@ -115,6 +121,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
       - name: Install RandR headers
         run: |
           sudo apt-get update
@@ -139,6 +147,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
 
       - name: set up JDK
         uses: actions/setup-java@v4
@@ -171,6 +181,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: "recursive"
+      - name: Update submodules
+        run: git submodule update --init --recursive
 
       - name: ccache
         uses: hendrikmuhs/ccache-action@v1.2.9

.github/workflows/check.yml

@@ -29,7 +29,7 @@ jobs:
         run: |
           git config --global --add safe.directory /__w/Vulkan-Samples/Vulkan-Samples
           git fetch origin $TARGET_BRANCH:$TARGET_BRANCH
-          echo all="$(git diff --name-only --diff-filter=ACMRT $TARGET_BRANCH | grep -v -e .github -e third_party -e .in$ | xargs)" >> $GITHUB_OUTPUT
+          echo all="$(git diff --name-only --diff-filter=ACMRT $TARGET_BRANCH | grep -v -e .github -e third_party -e 'samples/complex/render_octomap/octomap' -e .in$ | xargs)" >> $GITHUB_OUTPUT
 
   doxygen:
     name: Doxygen Syntax Check
@@ -101,7 +101,7 @@ jobs:
       - run: git config --global --add safe.directory /__w/Vulkan-Samples/Vulkan-Samples
       - run: cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DGLFW_BUILD_WAYLAND=OFF -Bbuild/clang
       - run: |
-          /usr/bin/run-clang-tidy -j $(($(nproc)/2+1)) -p build/clang -header-filter=framework,samples,app -checks=-*,google-*,-google-runtime-references -quiet ${{ needs.changed-files.outputs.all }}
+          /usr/bin/run-clang-tidy -j $(($(nproc)/2+1)) -p build/clang -header-filter=framework,samples,app -checks=-*,google-*,-google-runtime-references -quiet ${{ needs.changed-files.outputs.all }} 2>&1 | grep -v "third_party/glfw"
 
   pre-commit:
     name: Pre-Commit Checks

.gitmodules

@@ -56,3 +56,6 @@
 [submodule "third_party/ai-ml-sdk-vgf-library"]
 	path = third_party/ai-ml-sdk-vgf-library
 	url = https://github.com/arm/ai-ml-sdk-vgf-library
+[submodule "third_party/octomap"]
+	path = third_party/octomap
+	url = https://github.com/OctoMap/octomap.git

antora/modules/ROOT/nav.adoc

@@ -141,6 +141,10 @@
 * xref:samples/general/README.adoc[General samples]
 ** xref:samples/general/mobile_nerf/README.adoc[Mobile NeRF]
 ** xref:samples/general/mobile_nerf_rayquery/README.adoc[Mobile NeRF Ray Query]
+* xref:samples/complex/README.adoc[Complex Samples]
+** xref:samples/complex/render_octomap/README.adoc[Gausssian Splat and Octomap Rendering]
+*** xref:samples/complex/render_octomap/Tutorials/capturing-gaussian-splats.adoc[Capturing Gaussian Splats]
+*** xref:samples/complex/render_octomap/Tutorials/gaussian-splats-rendering.adoc[Rendering Gaussian Splats]
 * xref:docs/README.adoc[General documentation]
 ** xref:docs/build.adoc[Build guide]
 ** xref:docs/memory_limits.adoc[Memory limits]

assets

@@ -400,7 +400,8 @@ static inline bool texture_needs_srgb_colorspace(const std::string &name)
 }        // namespace
 
 std::unordered_map<std::string, bool> GLTFLoader::supported_extensions = {
-    {KHR_LIGHTS_PUNCTUAL_EXTENSION, false}};
+    {KHR_LIGHTS_PUNCTUAL_EXTENSION, false},
+    {KHR_GAUSSIAN_SPLATTING_EXTENSION, false}};
 
 GLTFLoader::GLTFLoader(vkb::core::DeviceC &device) :
     device{device}

framework/gltf_loader.cpp

@@ -35,6 +35,7 @@
 #include "vulkan/vulkan.h"
 
 #define KHR_LIGHTS_PUNCTUAL_EXTENSION "KHR_lights_punctual"
+#define KHR_GAUSSIAN_SPLATTING_EXTENSION "KHR_gaussian_splatting"
 
 namespace vkb
 {

framework/gltf_loader.h

@@ -1,5 +1,5 @@
 ////
-- Copyright (c) 2020-2024, Arm Limited and Contributors
+- Copyright (c) 2020-2026, Arm Limited and Contributors
 -
 - SPDX-License-Identifier: Apache-2.0
 -
@@ -44,3 +44,6 @@ include::./extensions/README.adoc[]
 
 [[tooling-samples]]
 include::./tooling/README.adoc[]
+
+[[complex-samples]]
+include::../complex/README.adoc[]

samples/README.adoc

@@ -0,0 +1,35 @@
+////
+- Copyright (c) 2021-2026, The Khronos Group
+-
+- SPDX-License-Identifier: Apache-2.0
+-
+- Licensed under the Apache License, Version 2.0 the "License";
+- you may not use this file except in compliance with the License.
+- You may obtain a copy of the License at
+-
+-     http://www.apache.org/licenses/LICENSE-2.0
+-
+- Unless required by applicable law or agreed to in writing, software
+- distributed under the License is distributed on an "AS IS" BASIS,
+- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+- See the License for the specific language governing permissions and
+- limitations under the License.
+-
+////
+ifndef::complex_samplespath[:complex_samplespath:]
+
+== Complex samples
+
+The goal of these samples is to demonstrate how to use Vulkan in a real world scenario.  These are meant to be demonstrations of how to use Vulkan as a whole instead of a singular item within Vulkan.
+
+This format for samples is to demonstrate how to work with other libraries or setup projects.  Some of the samples may or may not use the Framework as needed.
+
+While the Vulkan concepts found here aren't complex, the interaction and unique benefit with the real-world use cases they work with are meant to be.  Examples of what might eventually be found here include AI, OpenXR, GLTF, etc.  Topics which don't belong in the other sample categories by themselves yet are useful in many areas.
+
+=== xref:./{complex_samplespath}render_octmap/README.adoc[Render an Octo-Map]
+
+*Instancing*: https://docs.vulkan.org/spec/latest/chapters/drawing.html#vkCmdDrawIndexed[`vkCmdDrawIndexed`]
+
+Uses instancing to render octmaps generated in realtime by ARCore and ARKit then saved, and joined together using Point Cloud Registration into one shared map.
+
+These maps are commonly used by Robot Operating System (ROS) and this is a solution showing how to render the map created.  This is a topic of interest to SLAM and AI with OpenXR for map understanding and joining.

samples/complex/README.adoc

@@ -0,0 +1,72 @@
+# Copyright (c) 2025-2026, Holochip Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 the "License";
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+get_filename_component(FOLDER_NAME ${CMAKE_CURRENT_LIST_DIR} NAME)
+get_filename_component(PARENT_DIR ${CMAKE_CURRENT_LIST_DIR} PATH)
+get_filename_component(CATEGORY_NAME ${PARENT_DIR} NAME)
+
+# On Windows, build as STATIC to avoid DLL export issues
+# On other platforms, build as SHARED for better memory efficiency
+if(WIN32)
+    set(OCTOMAP_LIBRARY_TYPE STATIC)
+else()
+    set(OCTOMAP_LIBRARY_TYPE SHARED)
+endif()
+
+set(OCTOMAP_ROOT ${CMAKE_SOURCE_DIR}/third_party/octomap)
+
+add_library( octomath STATIC
+        ${OCTOMAP_ROOT}/octomap/src/math/Vector3.cpp
+        ${OCTOMAP_ROOT}/octomap/src/math/Quaternion.cpp
+        ${OCTOMAP_ROOT}/octomap/src/math/Pose6D.cpp
+)
+set_target_properties(octomath PROPERTIES POSITION_INDEPENDENT_CODE ON)
+target_include_directories(octomath PUBLIC ${OCTOMAP_ROOT}/octomap/include)
+
+add_library(octomap ${OCTOMAP_LIBRARY_TYPE}
+        ${OCTOMAP_ROOT}/octomap/src/AbstractOcTree.cpp
+        ${OCTOMAP_ROOT}/octomap/src/AbstractOccupancyOcTree.cpp
+        ${OCTOMAP_ROOT}/octomap/src/Pointcloud.cpp
+        ${OCTOMAP_ROOT}/octomap/src/ScanGraph.cpp
+        ${OCTOMAP_ROOT}/octomap/src/CountingOcTree.cpp
+        ${OCTOMAP_ROOT}/octomap/src/OcTree.cpp
+        ${OCTOMAP_ROOT}/octomap/src/OcTreeNode.cpp
+        ${OCTOMAP_ROOT}/octomap/src/OcTreeStamped.cpp
+        ${OCTOMAP_ROOT}/octomap/src/ColorOcTree.cpp
+)
+target_link_libraries(octomap PUBLIC octomath)
+
+add_library(dynamicEDT3d ${OCTOMAP_LIBRARY_TYPE} ${OCTOMAP_ROOT}/dynamicEDT3D/src/dynamicEDT3D.cpp)
+target_include_directories(dynamicEDT3d PUBLIC ${OCTOMAP_ROOT}/dynamicEDT3D/include)
+target_link_libraries(dynamicEDT3d PUBLIC octomap)
+
+add_sample_with_tags(
+        ID ${FOLDER_NAME}
+        CATEGORY ${CATEGORY_NAME}
+        AUTHOR "Holochip"
+        NAME "Octmap rendering"
+        DESCRIPTION "Demonstration of how to render an OctMap which was generated from ICP combining ARCore and ARKit SLAM maps"
+        SHADER_FILES_GLSL
+        "render_octomap/glsl/render.vert"
+        "render_octomap/glsl/render.frag"
+        "render_octomap/glsl/gltf.vert"
+        "render_octomap/glsl/gltf.frag"
+        "render_octomap/glsl/splat.vert"
+        "render_octomap/glsl/splat.frag"
+        LIBS
+            dynamicEDT3d
+)