Physics simulation engine implemented, basic cases (null and 2d SideScroller) works

This commit is contained in:
2026-05-26 10:36:31 -04:00
parent d87c5d2c20
commit 314ce5e10d
8 changed files with 271 additions and 26 deletions

186
src/physics.c Normal file
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#include <akstdlib.h>
#include <akgl/physics.h>
#include <akgl/actor.h>
#include <akgl/game.h>
#include <akgl/error.h>
#include <akgl/heap.h>
#include <akgl/registry.h>
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_null_gravity(akgl_PhysicsBackend *self, akgl_Actor *actor, SDL_Time curtime)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_null_collide(akgl_PhysicsBackend *self, akgl_Actor *a1, akgl_Actor *a2)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_null_move(struct akgl_PhysicsBackend *self, akgl_Actor *actor, SDL_Time curtime)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_init_null(akgl_PhysicsBackend *self)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
self->gravity = akgl_physics_null_gravity;
self->collide = akgl_physics_null_collide;
self->move = akgl_physics_null_move;
self->simulate = akgl_physics_simulate;
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_ss_gravity(akgl_PhysicsBackend *self, akgl_Actor *actor, SDL_Time curtime)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
// Do nothing
// Calculate the drop of all relevant actors which is a function of their mass and the
// world's gravity
//Gravity is applied in units per second. So we apply
// (unit / milliseconds per second) * (milliseconds since last update)
actor->vx += ((self->gravity_x / AKGL_TIME_ONESEC_NS) * (curtime - self->gravity_time));
actor->vy += ((self->gravity_y / AKGL_TIME_ONESEC_NS) * (curtime - self->gravity_time));
actor->vz += ((self->gravity_z / AKGL_TIME_ONESEC_NS) * (curtime - self->gravity_time));
// Apply atmospheric drag
actor->vx -= actor->vx * self->drag_x * (curtime - self->gravity_time);
actor->vy -= actor->vy * self->drag_x * (curtime - self->gravity_time);
actor->vz -= actor->vz * self->drag_x * (curtime - self->gravity_time);
// Need a euler function
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_ss_collide(akgl_PhysicsBackend *self, akgl_Actor *a1, akgl_Actor *a2)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
FAIL_RETURN(e, AKERR_API, "Not implemented");
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_ss_move(struct akgl_PhysicsBackend *self, akgl_Actor *actor, SDL_Time curtime)
{
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
FAIL_ZERO_RETURN(e, actor, AKERR_NULLPOINTER, "actor");
if ( actor->parent != NULL ) {
// Children don't move independently of their parents, they just have an offset
SUCCEED_RETURN(e);
} else if ( actor->basechar == NULL ) {
SUCCEED_RETURN(e);
} else {
if ( (curtime - actor->movetimer) >= actor->basechar->speedtime ) {
actor->movetimer = curtime;
ATTEMPT {
CATCH(e, actor->movementlogicfunc(actor,curtime));
} CLEANUP {
} PROCESS(e) {
} HANDLE(e, AKGL_ERR_LOGICINTERRUPT) {
// The actor told us NOT to process them, they handled their own update
SUCCEED_RETURN(e);
} FINISH(e, true);
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_LEFT) ) {
actor->x += -actor->vx;
}
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_RIGHT) ) {
actor->x += actor->vx;
}
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_UP) ) {
actor->y += -actor->vy;
}
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_DOWN) ) {
actor->y += actor->vy;
}
}
}
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_init_sidescroller(akgl_PhysicsBackend *self)
{
akgl_String *tmp;
PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
PASS(e, akgl_heap_next_string(&tmp));
self->gravity = akgl_physics_ss_gravity;
self->collide = akgl_physics_ss_collide;
self->move = akgl_physics_ss_move;
self->simulate = akgl_physics_simulate;
ATTEMPT {
CATCH(e, akgl_get_property("physics.gravity.x", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->gravity_x));
CATCH(e, akgl_get_property("physics.gravity.y", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->gravity_y));
CATCH(e, akgl_get_property("physics.gravity.z", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->gravity_z));
CATCH(e, akgl_get_property("physics.drag.x", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->drag_x));
CATCH(e, akgl_get_property("physics.drag.y", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->drag_y));
CATCH(e, akgl_get_property("physics.drag.z", &tmp, "0.0"));
CATCH(e, aksl_atof(tmp->data, &self->drag_z));
} CLEANUP {
IGNORE(akgl_heap_release_string(tmp));
} PROCESS(e) {
} FINISH(e, true);
SUCCEED_RETURN(e);
}
akerr_ErrorContext AKERR_NOIGNORE *akgl_physics_simulate(akgl_PhysicsBackend *self, akgl_Iterator *opflags)
{
PREPARE_ERROR(e);
akgl_Iterator defflags = {
.flags = 0,
.layerid = 0
};
SDL_Time curtime = SDL_GetTicksNS();
akgl_Actor *actor = NULL;
FAIL_ZERO_RETURN(e, self, AKERR_NULLPOINTER, "self");
FAIL_ZERO_RETURN(e, self->move, AKERR_NULLPOINTER, "self->move");
if ( opflags == NULL ) {
opflags = &defflags;
}
for ( int i = 0; i < AKGL_MAX_HEAP_ACTOR; i++ ) {
actor = &HEAP_ACTOR[i];
if ( actor->refcount == 0 ) {
continue;
}
if ( AKGL_BITMASK_HAS(opflags->flags, AKGL_ITERATOR_OP_LAYERMASK) ) {
if ( actor->layer != opflags->layerid ) {
continue;
}
}
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_LEFT) ||
AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_RIGHT) ) {
actor->vx += actor->basechar->ax;
}
if ( AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_UP) ||
AKGL_BITMASK_HAS(actor->state, AKGL_ACTOR_STATE_MOVING_DOWN) ) {
actor->vy += actor->basechar->ay;
}
PASS(e, self->gravity(self, actor, curtime));
PASS(e, self->move(self, actor, curtime));
self->gravity_time = curtime;
}
SUCCEED_RETURN(e);
}