asteroids/main.c

#include "raylib.h"
#include "raymath.h"
#include <math.h>
#include <stdio.h>

#define DRAG -0.001f

typedef struct ship_t {
  Vector2 position;
  Vector2 velocity;
  Vector2 accel;
  Vector2 size;
  Vector2 direction;
  float angle;
} ship;

typedef struct game_g {
  ship s;
  float dt;
} game;

game g;

void ship_draw(const ship *s) { DrawRectangleV(s->position, s->size, BLACK); }

void ship_up(ship *s) {

  Vector2 min = {.x = -1000.0f, .y = -1000.0f};
  Vector2 max = {.x = 1000.0f, .y = 1000.0f};

  Vector2 diff = Vector2Subtract(s->direction, s->position);

  Vector2 accellv = CLITERAL(Vector2){.x = diff.x, .y = diff.y};
  Vector2Normalize(accellv);
  s->accel = Vector2Add(accellv, s->accel);

  s->accel = Vector2Clamp(s->accel, min, max);
}

void ship_stop(ship *s) {

  Vector2 min = {.x = 1.0, .y = 1.0};
  Vector2 max = {.x = 0.0, .y = 0.0};
  s->accel.y -= 0.0001f;
  s->accel.x -= 0.0001f;
  s->accel = Vector2Clamp(s->accel, min, max);
}

void ship_update(ship *s) {
  Vector2 drag = {.x = DRAG * s->velocity.x, .y = DRAG * s->velocity.y};

  float x = cosf(s->angle);
  float y = sinf(s->angle);

  Vector2 polar = CLITERAL(Vector2){.x = x, .y = y};
  Vector2 pos = Vector2Add(s->position, polar);

  float x1 = 100 * cosf(s->angle);
  float y1 = 100 * sinf(s->angle);

  Vector2 polar1 = CLITERAL(Vector2){.x = x1, .y = y1};
  Vector2 pos1 = Vector2Add(s->position, polar1);

  s->direction.x = pos.x;
  s->direction.y = pos.y;

  s->velocity.x += s->accel.x * g.dt;
  s->velocity.y += s->accel.y * g.dt;
  s->velocity = Vector2Add(s->velocity, drag);

  s->position.x += s->velocity.x * g.dt;
  s->position.y += s->velocity.y * g.dt;

  DrawLine(s->position.x, s->position.y, pos1.x, pos1.y, RED);
}

void process_inputs(game *g) {
  if (IsKeyDown(KEY_W)) {
    ship_up(&g->s);
  } else {
    ship_stop(&g->s);
  }
  if (IsKeyDown(KEY_D)) {
    g->s.angle += 1.0f * g->dt;
  }
  if (IsKeyDown(KEY_A)) {
    g->s.angle -= 1.0f * g->dt;
  }
}

void text(const game *g) {
  char ind[256] = {0};
  sprintf(ind,
          "ship position %fx%f\nship speed %fx%f\nship accel %fx%f\nangle: "
          "%f\ndirection %fx%f",
          g->s.position.x, g->s.position.y, g->s.velocity.x, g->s.velocity.y,
          g->s.accel.x, g->s.accel.y, g->s.angle, g->s.direction.x,
          g->s.direction.y);
  DrawText(ind, 10, 10, 20, BLACK);
}

int main(void) {

  InitWindow(1820, 900, "Hello World");

  ship s1 = {0};
  s1.position.x = 910.0f;
  s1.position.y = 450.0f;

  s1.size.x = 10.0f;
  s1.size.y = 10.0f;
  s1.angle = 3 * PI / 2;

  g.s = s1;

  while (!WindowShouldClose()) {
    BeginDrawing();
    ClearBackground(WHITE);
    process_inputs(&g);
    ship_draw(&g.s);
    ship_update(&g.s);
    text(&g);
    EndDrawing();

    g.dt = GetFrameTime();
  }

  return (0);
}