Open the jni/GraphicsManager.hpp header and include the headers:

Then, remove the textureResource member in the TextureProperties structure. Use a map container instead of a raw array for mTextures (prefixed with the std namespace). The first parameter is the key type and the second the value type.

Finally, replace all the other raw arrays with a vector, as shown in the following:

...
#include <android_native_app_glue.h>
#include <GLES2/gl2.h>
#include <EGL/egl.h>

#include <map>
#include <vector>
...
struct TextureProperties {
    GLuint texture;
    int32_t width;
    int32_t height;
};

class GraphicsManager {
    ...
    // Graphics...