Add CMakeLists.txt files for new (experimental) code.

This includes the filament, toolbox, and studio projects.

Adds a MUJOCO_BUILD_STUDIO option to enable building of the `studio` app (disabled by default).

Adds a MUJOCO_USE_FILAMENT to allow the studio app to use the filament rendering backend. A separate MUJOCO_USE_FILAMENT_VULKAN flag can be used to enable vulkan rendering.

PiperOrigin-RevId: 824602367
Change-Id: I26d46c16211ae2118f96c163c4194fea5b5a15a9

src/experimental/toolbox/CMakeLists.txt

@@ -0,0 +1,56 @@
+# Copyright 2025 DeepMind Technologies Limited
+#
+# 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
+#
+#     https://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.
+
+cmake_minimum_required(VERSION 3.16)
+
+set(MUJOCO_TOOLBOX_TARGET_NAME mujoco_toolbox)
+
+add_library(${MUJOCO_TOOLBOX_TARGET_NAME} STATIC)
+
+target_sources(${MUJOCO_TOOLBOX_TARGET_NAME}
+    PUBLIC
+        helpers.cc
+        helpers.h
+        imgui_widgets.cc
+        imgui_widgets.h
+        interaction.cc
+        interaction.h
+        physics.cc
+        physics.h
+        renderer.cc
+        renderer.h
+        step_control.cc
+        step_control.h
+        window.cc
+        window.h
+)
+target_include_directories(${MUJOCO_TOOLBOX_TARGET_NAME}
+    PUBLIC
+        ${PROJECT_SOURCE_DIR}/include
+        ${PROJECT_SOURCE_DIR}/src
+)
+
+include(third_party_deps/dear_imgui)
+include(third_party_deps/implot)
+include(third_party_deps/sdl2)
+include(third_party_deps/libwebp)
+
+target_link_libraries(${MUJOCO_TOOLBOX_TARGET_NAME}
+    dear_imgui
+    implot
+    webp
+    SDL2::SDL2-static
+)
+
+add_library(mujoco::toolbox ALIAS ${MUJOCO_TOOLBOX_TARGET_NAME})