From 199febefb670f227ceb2824b086f476e4362ca28 Mon Sep 17 00:00:00 2001
From: kallaballa <amir@viel-zu.org>
Date: Tue, 11 Apr 2023 20:52:13 +0200
Subject: [PATCH] GLES3 adaption

---
 modules/viz2d/CMakeLists.txt                   |  3 ++-
 modules/viz2d/include/opencv2/viz2d/dialog.hpp |  9 +++++++++
 modules/viz2d/include/opencv2/viz2d/viz2d.hpp  |  9 ++++++++-
 modules/viz2d/samples/cpp/Makefile             |  1 +
 modules/viz2d/src/dialog.cpp                   | 10 ++++++++++
 5 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/modules/viz2d/CMakeLists.txt b/modules/viz2d/CMakeLists.txt
index cf2648ec3..d58969d39 100644
--- a/modules/viz2d/CMakeLists.txt
+++ b/modules/viz2d/CMakeLists.txt
@@ -18,12 +18,13 @@ elseif(NOT nanovg_FOUND)
 elseif(NOT nanogui_FOUND)
   message(STATUS "Module opencv_viz2d disabled because NanoGUI was not found")
   ocv_module_disable(viz2d)
-else() # we need C++20
+else()
   if(MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Qstd=c++20")
   else()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++20")
   endif()
+#  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DVIZ2D_USE_ES3=1")
 endif()
 
 include_directories(${glfw3_INCLUDE_DIRS})
diff --git a/modules/viz2d/include/opencv2/viz2d/dialog.hpp b/modules/viz2d/include/opencv2/viz2d/dialog.hpp
index 2f4304374..f19aaae78 100644
--- a/modules/viz2d/include/opencv2/viz2d/dialog.hpp
+++ b/modules/viz2d/include/opencv2/viz2d/dialog.hpp
@@ -5,7 +5,16 @@
 
 #ifndef SRC_COMMON_DIALOG_HPP_
 #define SRC_COMMON_DIALOG_HPP_
+#ifdef __EMSCRIPTEN__
+#define VIZ2D_USE_ES3 1
+#endif
 
+#ifndef VIZ2D_USE_ES3
+#define NANOGUI_USE_OPENGL
+#else
+#define NANOGUI_USE_GLES
+#define NANOGUI_GLES_VERSION 3
+#endif
 #include <nanogui/nanogui.h>
 #include <opencv2/opencv.hpp>
 
diff --git a/modules/viz2d/include/opencv2/viz2d/viz2d.hpp b/modules/viz2d/include/opencv2/viz2d/viz2d.hpp
index 401e10b7e..842de2478 100644
--- a/modules/viz2d/include/opencv2/viz2d/viz2d.hpp
+++ b/modules/viz2d/include/opencv2/viz2d/viz2d.hpp
@@ -17,11 +17,18 @@
 #include <string>
 #include <opencv2/opencv.hpp>
 #include <opencv2/videoio.hpp>
-#include <nanogui/nanogui.h>
 #ifdef __EMSCRIPTEN__
 #define VIZ2D_USE_ES3 1
 #include <emscripten.h>
 #endif
+
+#ifndef VIZ2D_USE_ES3
+#define NANOGUI_USE_OPENGL
+#else
+#define NANOGUI_USE_GLES
+#define NANOGUI_GLES_VERSION 3
+#endif
+#include <nanogui/nanogui.h>
 #ifndef VIZ2D_USE_ES3
 #include <GL/glew.h>
 #else
diff --git a/modules/viz2d/samples/cpp/Makefile b/modules/viz2d/samples/cpp/Makefile
index 6ce89c754..b14c24929 100644
--- a/modules/viz2d/samples/cpp/Makefile
+++ b/modules/viz2d/samples/cpp/Makefile
@@ -4,6 +4,7 @@ ifdef EMSDK
 LDFLAGS  := -flto -L/usr/local/lib/ -L../common
 LIBS     := -lopencv_core -lopencv_imgproc -lnanogui
 else
+#CXXFLAGS += -DVIZ2D_USE_ES3=1
 LDFLAGS  := -L/opt/local/lib -flto -L/usr/local/lib64 -L../common/ -L/usr/local/lib
 LIBS     := -lnanogui
 endif
diff --git a/modules/viz2d/src/dialog.cpp b/modules/viz2d/src/dialog.cpp
index 11bea4234..ca5927a0a 100644
--- a/modules/viz2d/src/dialog.cpp
+++ b/modules/viz2d/src/dialog.cpp
@@ -5,6 +5,16 @@
 
 #include "opencv2/viz2d/dialog.hpp"
 #include <nanogui/layout.h>
+#ifdef __EMSCRIPTEN__
+#define VIZ2D_USE_ES3 1
+#endif
+#ifndef VIZ2D_USE_ES3
+#  include <GL/glew.h>
+#  define GLFW_INCLUDE_GLCOREARB
+#else
+#  define GLFW_INCLUDE_ES3
+#  define GLFW_INCLUDE_GLEXT
+#endif
 #include <GLFW/glfw3.h>
 
 namespace cv {