3D Shooters for Quake II - Pro Android Games - page 233

6. Finally, invoke Quake II main sub with the arguments that you

just created.

// Invoke Quake's main sub.
main (clen, args);

Rendering a Single Frame
Both the Java and C implementations for RenderFrame are the same as Chapter 6. In
Natives.java you declared the native method RenderFrame() , which is implemented as
shown in the following fragment:

extern void RenderFrame();

JNIEXPORT jint JNICALL Java_quake_jni_Natives_RenderFrame
(JNIEnv * env, jclass cls)
{
RenderFrame();
}

The C keyword extern next to void RenderFrame() tells the compiler that elsewhere
exists a function called RenderFrame , which will be invoked within the JNI implementation.
RenderFrame is a new function and needs to be created.
Listing 7-1 shows the Quake II main function from the project source at ch07.QuakeII/jni/
quake2-3.21/android/sys_linux.c . You notice that it loops forever (by using a while (1) loop).

Listing 7-1. Quake II Main Function

int main (int argc, char **argv)
{
int time, oldtime, newtime;
// go back to real user for config loads
saved_euid = geteuid();
seteuid(getuid());

Qcommon_Init(argc, argv);

nostdout = Cvar_Get("nostdout", "0", 0);
if (!nostdout->value) {
printf ("Linux Quake -- Version %0.3f\n", LINUX_VERSION);
}
oldtime = Sys_Milliseconds ();

// main render loop
while (1) {
// find time spent rendering last frame
do {
newtime = Sys_Milliseconds ();