DimOrbit is a Newtonian spacecraft/orbit simulator based on my Raylib wrapper/game engine DimEngineZ. It is meant to be simple and easy-to-use.
Warning
Some changes are made to DimEngineZ directly from DimOrbit without modifying the original copy. This may include bug fixes that may not be mirrored immediately to DimEngineZ.
Here's an example of the sun, an XZ Clue plane, and a spacecraft called "Explorer" that orbits around it.
#include <DimOrbit/DimOrbit.h>
int main(int, char**) {
// aliases
namespace dez = DimEngineZ;
namespace dor = DimOrbit;
using Vec3 = DimEngineZ::Vec3;
// initialization
dez::manager::init(1000, 800, "Mission Simulation");
auto camera = dez::Camera(Vec3{3.0, 3.0, 3.0}, dez::CameraOptions{
.fovy = 110.0,
});
camera.setTarget(Vec3::ZERO);
auto system = dor::CelestialSystem();
auto renderer = dor::Renderer();
renderer.enableXZClue(true);
renderer.xzclue.height = 0.0f;
auto clock = dor::Clock(system);
auto controller = dor::Controller();
controller.bindVec3(
"move", KEY_SPACE, KEY_LEFT_SHIFT, KEY_A, KEY_D, KEY_W,
KEY_S); // forward and backward are inverted because of look-around weirdness
controller.bindVec2("look", KEY_T, KEY_G, KEY_F, KEY_H);
controller.bindVec3("thrust", KEY_RIGHT_SHIFT, KEY_KP_1, KEY_LEFT, KEY_RIGHT, KEY_DOWN, KEY_UP);
// bodies
auto earth = system.addBody(dor::BodyOptions{
.name = "Earth",
.radius = 1.0,
.color = GREEN,
.mass = 1.0,
.collide = false,
});
auto spacecraft = system.addSpacecraft(dor::BasicSpacecraftOptions{
.name = "Spacecraft",
.radius = 0.1,
.color = RED,
.mass = 1e-9,
.collide = false,
.specificImpulse = 1e-9,
});
spacecraft->engine.start(spacecraft->physics->core.mass); // sets throttle
// scales down thrust to be appropriate to the mass
spacecraft->body->beginCircularOrbit(*earth.get(), 3.0, PI);
// constants
constexpr float CAM_SPEED = 3.0f;
constexpr float CAM_LOOK_SPEED = 1.75f;
constexpr float THRUST_MULTIPLIER = 2.0f;
// main loop
int exit_code = dez::manager::fixedloop(
60, 60,
// physics
[&](float delta) {
Vec3 movVec = controller.getVec3("move") * delta * CAM_SPEED;
camera.moveForward(movVec.z);
camera.moveRight(movVec.x);
camera.moveUp(movVec.y);
dez::Vec2 lookVec = controller.getVec2("look") * CAM_LOOK_SPEED;
camera.lookAround(-lookVec.x * delta, lookVec.y * delta);
Vec3 thrust = controller.getVec3("thrust") * THRUST_MULTIPLIER;
spacecraft->engine.setMaxThrust(thrust);
clock.tick(delta);
return true;
},
// rendering
[&]() {
renderer.doindraw(BLACK, [&]() {
renderer.doin3d(camera, [&]() {
// render the system in 3d mode
renderer.render(system);
renderer.displayVector(spacecraft->physics->core.velocity,
spacecraft->physics->transform.position, YELLOW);
renderer.displayVector(spacecraft->engine.maxThrust,
spacecraft->physics->transform.position, RED);
return 0;
});
renderer.renderName(*spacecraft.get(), GREEN);
renderer.draw2DLabel(clock.time.getUTCTime(), dez::Vec2::ZERO);
return 0;
});
return true;
});
return exit_code;
}As you can see, there is a strong separation between the actual physics (dor::CelestialSystem) and other aspects of the simulation (dor::Renderer, dor::Clock, dor::Controller). Things such as labels, vectors, and drawing in general are handled exclusively by the Renderer.