fix: include ptcloud header and dependency for opengl_testdata_generator sample #29293
## Summary
Fixes the build failure in samples/opengl/opengl_testdata_generator.cpp on the 5.x
branch when building with BUILD_EXAMPLES=ON.
## Root cause
The sample uses `loadMesh`, `TriangleShadingType`, and `TriangleCullingMode`, all
declared in `modules/ptcloud/include/opencv2/ptcloud.hpp`. The sample did not
include this header, and `samples/opengl/CMakeLists.txt` did not list
`opencv_ptcloud` as a required dependency, so the ptcloud module headers/libs
were not available when compiling this sample.
## Changes
- Added `#include "opencv2/ptcloud.hpp"` to opengl_testdata_generator.cpp
- Added `opencv_ptcloud` to `OPENCV_OPENGL_SAMPLES_REQUIRED_DEPS` in
samples/opengl/CMakeLists.txt
## Acceptance criteria
- [x] opengl_testdata_generator.cpp compiles with BUILD_EXAMPLES=ON
- [x] ptcloud module dependency declared so build system links it correctly
Closes#29292
Fix mesh loading for texture coordinates and face indices #25382
### This PR changes
* Texture coordinates were stored incorrectly (3-channel array is read as if there were 2 channels), fixed
* Faces were pushed back to the output array instead of indexed writing which produced a lot of empty faces, fixed
* A set of ground truth tests were added to cover these issues
* `std::vector<cv::Mat>` support added for `saveMesh()` which is required for Python bindings
* More command line args were added to rasterization test data generator
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
Triangle rasterization function #24459#24065 reopened since the previous one was automatically closed after rebase
Connected PR with ground truth data: [#1113@extra](https://github.com/opencv/opencv_extra/pull/1113)
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
Maitreyee Deshmukh
Alexander Smorkalov
Rostislav Vasilikhin
Rostislav Vasilikhin