Add CMake configurations for new third_party dependencies.

Adds targets for dear_imgui, implot, filament, sdl2, and webp. These
targets are not currently used.

PiperOrigin-RevId: 824554405
Change-Id: Ibebdd50752d251852a945b6abc230e2c6e65fae9

cmake/third_party_deps/dear_imgui/CMakeLists.txt

@@ -0,0 +1,61 @@
+# 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.
+
+add_library(dear_imgui STATIC)
+target_include_directories(dear_imgui
+  PUBLIC
+    ${dear_imgui_SOURCE_DIR}
+)
+target_sources(dear_imgui
+  PUBLIC
+    ${dear_imgui_SOURCE_DIR}/imgui.h
+    ${dear_imgui_SOURCE_DIR}/imgui.cpp
+    ${dear_imgui_SOURCE_DIR}/imgui_internal.h
+    ${dear_imgui_SOURCE_DIR}/imgui_draw.cpp
+    ${dear_imgui_SOURCE_DIR}/imgui_tables.cpp
+    ${dear_imgui_SOURCE_DIR}/imgui_widgets.cpp
+    ${dear_imgui_SOURCE_DIR}/imgui_demo.cpp
+)
+
+# SDL2 backend
+# TODO: I don't know how to correctly check for dependencies in cmake. This
+# assumes that SDL2 is pulled in _before_ dear_imgui, but that seems fragile.
+# For now, we'll just assume SDL2 is available as dear_imgui is only being used
+# in contexts which depend on SDL2.
+#if(TARGET SDL2)
+  add_library(dear_imgui_SDL2 STATIC)
+  target_include_directories(dear_imgui_SDL2
+    PUBLIC
+      ${dear_imgui_SOURCE_DIR}
+  )
+  target_sources(dear_imgui_SDL2
+    PUBLIC
+      ${dear_imgui_SOURCE_DIR}/backends/imgui_impl_sdl2.cpp
+  )
+  target_link_libraries(dear_imgui_SDL2
+    SDL2::SDL2-static
+  )
+#endif()
+
+# OpenGL3 backend
+add_library(dear_imgui_OpenGL3 STATIC)
+target_include_directories(dear_imgui_OpenGL3
+  PUBLIC
+    ${dear_imgui_SOURCE_DIR}
+)
+target_sources(dear_imgui_OpenGL3
+  PUBLIC
+    ${dear_imgui_SOURCE_DIR}/backends/imgui_impl_opengl3.h
+    ${dear_imgui_SOURCE_DIR}/backends/imgui_impl_opengl3.cpp
+)

cmake/third_party_deps/implot/CMakeLists.txt

@@ -0,0 +1,33 @@
+# 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.
+
+add_library(implot STATIC)
+
+target_include_directories(implot
+  PUBLIC
+    ${implot_SOURCE_DIR}
+)
+
+target_sources(implot
+  PUBLIC
+    ${implot_SOURCE_DIR}/implot.h
+    ${implot_SOURCE_DIR}/implot_internal.h
+    ${implot_SOURCE_DIR}/implot.cpp
+    ${implot_SOURCE_DIR}/implot_items.cpp
+    ${implot_SOURCE_DIR}/implot_demo.cpp
+)
+
+target_link_libraries(implot
+  dear_imgui
+)