Add a depth camera example (#467)

* [Metal] add a depth_camera example

- Add example for a depth camera.
- Based on the segmentation_camera and thermal_camera examples.
- Includes code for converting images to grayscale copied from ign-senors.

Signed-off-by: Rhys Mainwaring <[email protected]>

* [Metal] document the depth_camera example

- Add markup for code snippets.
- Add a tutorial page and image.
- Update the main tutorials page.

Signed-off-by: Rhys Mainwaring <[email protected]>

* [Metal] improve documentation

- Incorporate review feedback from @iche033

Signed-off-by: Rhys Mainwaring <[email protected]>

Co-authored-by: Ian Chen <[email protected]>

examples/depth_camera/CMakeLists.txt

@@ -0,0 +1,39 @@
+cmake_minimum_required(VERSION 3.10.2 FATAL_ERROR)
+project(ignition-rendering-depth-camera)
+find_package(ignition-rendering6 REQUIRED)
+
+include_directories(SYSTEM
+  ${PROJECT_BINARY_DIR}
+)
+
+find_package(GLUT REQUIRED)
+include_directories(SYSTEM ${GLUT_INCLUDE_DIRS})
+link_directories(${GLUT_LIBRARY_DIRS})
+
+find_package(OpenGL REQUIRED)
+include_directories(SYSTEM ${OpenGL_INCLUDE_DIRS})
+link_directories(${OpenGL_LIBRARY_DIRS})
+
+if (NOT APPLE)
+  find_package(GLEW REQUIRED)
+  include_directories(SYSTEM ${GLEW_INCLUDE_DIRS})
+  link_directories(${GLEW_LIBRARY_DIRS})
+endif()
+
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-deprecated-declarations")
+
+configure_file (example_config.hh.in ${PROJECT_BINARY_DIR}/example_config.hh)
+
+add_executable(depth_camera Main.cc GlutWindow.cc)
+
+target_link_libraries(depth_camera
+  ${GLUT_LIBRARIES}
+  ${OPENGL_LIBRARIES}
+  ${GLEW_LIBRARIES}
+  ${IGNITION-RENDERING_LIBRARIES}
+)
+
+add_custom_command(TARGET depth_camera POST_BUILD
+  COMMAND ${CMAKE_COMMAND} -E copy_directory
+  ${CMAKE_SOURCE_DIR}/media
+  $<TARGET_FILE_DIR:depth_camera>/media)