The next step is to cause the panda to actually
move back and forth. Add the following lines of code:
#include "pandaFramework.h"
#include "pandaSystem.h"
#include "cIntervalManager.h"
#include "cLerpNodePathInterval.h"
#include "cMetaInterval.h"
PandaFramework framework;
int main(int argc, char *argv[]) {
//open a new window framework and set title
framework.open_framework(argc, argv);
framework.set_window_title("My Panda3D Window");
//open the window
WindowFramework *window = framework.open_window();
NodePath cam = window->get_camera_group(); //get the camera and store it
//load the environment model
NodePath environ = window->load_model(framework.get_models(),"models/environment");
environ.reparent_to(window->get_render());
environ.set_scale(0.25,0.25,0.25);
environ.set_pos(-8,42,0);
//load our panda
NodePath pandaActor = window->load_model(framework.get_models(),"panda-model");
pandaActor.set_scale(0.005,0.005,0.005);
pandaActor.reparent_to(window->get_render());
//load the walk animation
window->load_model(pandaActor,"panda-walk4");
window->loop_animations(0);
//create the lerp intervals needed to walk back and forth
PT(CLerpNodePathInterval) pandaPosInterval1;
pandaPosInterval1 = new CLerpNodePathInterval("pandaPosInterval1",13.0,CLerpInterval::BT_no_blend,
true,false,pandaActor,window->get_render());
pandaPosInterval1->set_start_pos(LPoint3f(0,10,0));
pandaPosInterval1->set_end_pos(LPoint3f(0,-10,0));
PT(CLerpNodePathInterval) pandaPosInterval2;
pandaPosInterval2 = new CLerpNodePathInterval("pandaPosInterval2",13.0,CLerpInterval::BT_no_blend,
true,false,pandaActor,window->get_render());
pandaPosInterval2->set_start_pos(LPoint3f(0,-10,0));
pandaPosInterval2->set_end_pos(LPoint3f(0,10,0));
PT(CLerpNodePathInterval) pandaHprInterval1;
pandaHprInterval1 = new CLerpNodePathInterval("pandaHprInterval1",3.0,CLerpInterval::BT_no_blend,
true,false,pandaActor,window->get_render());
pandaHprInterval1->set_start_hpr(LPoint3f(0,0,0));
pandaHprInterval1->set_end_hpr(LPoint3f(180,0,0));
PT(CLerpNodePathInterval) pandaHprInterval2;
pandaHprInterval2 = new CLerpNodePathInterval("pandaHprInterval2",3.0,CLerpInterval::BT_no_blend,
true,false,pandaActor,window->get_render());
pandaHprInterval2->set_start_hpr(LPoint3f(180,0,0));
pandaHprInterval2->set_end_hpr(LPoint3f(0,0,0));
//create and play the sequence that coordinates the intervals
PT(CMetaInterval) pandaPace;
pandaPace = new CMetaInterval("pandaPace");
pandaPace->add_c_interval(pandaPosInterval1,0,CMetaInterval::RS_previous_end);
pandaPace->add_c_interval(pandaHprInterval1,0,CMetaInterval::RS_previous_end);
pandaPace->add_c_interval(pandaPosInterval2,0,CMetaInterval::RS_previous_end);
pandaPace->add_c_interval(pandaHprInterval2,0,CMetaInterval::RS_previous_end);
pandaPace->loop();
//do the main loop:
ClockObject* clock (ClockObject::get_global_clock()); //get the global clock object
Thread *current_thread = Thread::get_current_thread();
while(framework.do_frame(current_thread)) {
CIntervalManager::get_global_ptr()->step(); //step the interval manager
double time = clock->get_real_time(); //get the time in seconds
double angledegrees = time * 6.0; //the angle of the camera in degrees
double angleradians = angledegrees * (3.14 / 180.0); //in radians
cam.set_pos(20*sin(angleradians),-20.0*cos(angleradians),3); //set the position
cam.set_hpr(angledegrees, 0, 0); //set the hpr
}
//close the window framework
framework.close_framework();
return (0);
}
Intervals are tasks that change a property
from one value to another over a specified period of time. Starting
an interval effectively starts a background process that modifies the
property over the specified period of time. For example, consider the
pandaPosInterval1 above. When that interval is
started, it will gradually adjust the position of the panda from
(0,10,0) to (0,-10,0) over a period of 13 seconds. Similarly,
when the pandaHprInterval1 is started,
the orientation of the panda will rotate 180 degrees over a period of 3 seconds.
MetaIntervals are tasks that execute one interval
after another. The pandaPace sequence above
causes the panda to move in a straight line, then turn, then in the
opposite straight line, then to turn again. The code pandaPace->loop() causes the MetaInterval to be started
in looping mode.
The result of all this is to cause the panda to pace
back and forth from one tree to the other.
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