Android NDK Beginner's Guide - Second Edition

Time for action – displaying raw graphics

Let's make DroidBlaster more interactive with some graphics and game components.

1. Edit jni/Types.hpp and create a new structure Location to hold entity positions. Also, define a macro to generate a random value in the requested range as follows:

   #ifndef _PACKT_TYPES_HPP_
   #define _PACKT_TYPES_HPP_
   ...
   struct Location {
       Location(): x(0.0f), y(0.0f) {};
   
       float x; float y;
   };
   
   #define RAND(pMax) (float(pMax) * float(rand()) / float(RAND_MAX))
   #endif

2. Create a new file, jni/GraphicsManager.hpp. Define a structure GraphicsElement, which contains the location and dimensions of the graphical element to display:

   #ifndef _PACKT_GRAPHICSMANAGER_HPP_ #define _PACKT_GRAPHICSMANAGER_HPP_ #include "Types.hpp" #include <android_native_app_glue.h> ...