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142 lines
4.4 KiB
C

#include "types.h"
#include <stdlib.h> // malloc
#include <stdio.h>
void __assert(bool cond, const char * file, int line, const char * cond_string)
{
if(!cond)
{
fprintf(stderr, "%s:%d | Assertion %s failed\n", file, line, cond_string);
}
}
#define assert(condition) __assert(condition, __FILE__, __LINE__, #condition)
// do not use any global variables to process gamestate
// super try not to depend on external libraries like enet or sokol to keep build process simple,
// gamestate its own portable submodule. If need to link to other stuff document here:
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static void integrate_acceleration(struct Body *body, float dt)
{
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// position
{
V2 current = body->position;
body->position = V2add(body->position, V2sub(current, body->old_position));
body->position = V2add(body->position, V2scale(body->acceleration, dt * dt));
body->old_position = current;
}
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// rotation
{
float current = body->rotation;
body->rotation = body->rotation + (current - body->old_rotation);
body->rotation = body->rotation + body->angular_acceleration * dt * dt;
body->old_rotation = current;
}
}
static void modify_interval(struct Body *from, float *from_interval, V2 center, V2 axis)
{
float halfbox = BOX_SIZE/2.0f;
V2 points[4] = {
V2add(from->position, V2rotate((V2){.x = halfbox, .y = -halfbox}, from->rotation)), // upper right
V2add(from->position, V2rotate((V2){.x = halfbox, .y = halfbox}, from->rotation)), // bottom right
V2add(from->position, V2rotate((V2){.x = -halfbox, .y = halfbox}, from->rotation)), // lower left
V2add(from->position, V2rotate((V2){.x = -halfbox, .y = -halfbox}, from->rotation)), // upper left
};
for (int point_i = 0; point_i < 4; point_i++)
{
float value = V2projectvalue(V2sub(points[point_i], center), axis);
if (value > from_interval[1])
{
from_interval[1] = value;
}
if (value < from_interval[0])
{
from_interval[0] = value;
}
}
}
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void process(struct GameState *gs, float dt)
{
int num_bodies = gs->num_boxes;
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for (int i = 0; i < MAX_PLAYERS; i++)
{
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struct Player *p = &gs->players[i];
if (!p->connected)
continue;
p->body.acceleration = V2scale(p->input, 5.0f);
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p->body.angular_acceleration = p->input.x * 10.0f;
num_bodies += 1;
}
// @Robust do this without malloc
struct Body **bodies = malloc(sizeof *bodies * num_bodies);
int cur_body_index = 0;
for (int i = 0; i < MAX_PLAYERS; i++)
{
struct Player *p = &gs->players[i];
if (!p->connected)
continue;
bodies[cur_body_index] = &p->body;
cur_body_index++;
}
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for (int i = 0; i < gs->num_boxes; i++)
{
bodies[cur_body_index] = &gs->boxes[i].body;
cur_body_index++;
}
assert(cur_body_index == num_bodies);
for (int i = 0; i < num_bodies; i++)
{
struct Body *body = bodies[i];
integrate_acceleration(body, dt);
}
// @Robust handle when bodies are overlapping (even perfectly)
for (int i = 0; i < num_bodies; i++)
{
for (int ii = 0; ii < num_bodies; ii++)
{
if (ii == i)
continue;
struct Body *from = bodies[i];
struct Body *to = bodies[ii];
V2 axis = V2normalize(V2sub(to->position, from->position));
V2 center = V2scale(V2add(to->position, from->position), 0.5f);
dbg_line(from->position, to->position);
dbg_rect(center);
float from_interval[2] = {1000.0f, -1000.0f};
float to_interval[2] = {1000.0f, -1000.0f};
modify_interval(from, from_interval, center, axis);
modify_interval(to, to_interval, center, axis);
assert(from_interval[0] < from_interval[1]);
assert(to_interval[0] < to_interval[1]);
// @BeforeShip debug compile time flag in preprocessor
if (from_interval[1] > to_interval[0]) // intersecting
{
float intersection_depth = from_interval[1] - to_interval[0];
from->position = V2add(from->position, V2scale(axis, intersection_depth*-0.5f));
to->position = V2add(to->position, V2scale(axis, intersection_depth*0.5f));
}
}
}
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free(bodies);
}