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#include "plugin.h"
#include <gfx/gfx.h>
#include <gfx/gfx_app.h>
#include <gfx/renderer.h>
#include <math/mat4.h>
#include <math/vec2.h>
#include <math/vec4.h>
#include <stdlib.h>
static const vec2 PAD_SIZE = (vec2){120, 20};
static const R PLAYER_Y_OFFSET = 50;
static const R PLAYER_SPEED = 800;
static const R ENEMY_SPEED = 2;
static const R BALL_SIZE = 18;
static const R BALL_SPEED = 360; // In each dimension.
static const R EPS = (R)1e-3;
typedef struct Player {
vec2 position;
} Player;
typedef struct Ball {
vec2 position;
vec2 velocity;
} Ball;
typedef struct State {
bool game_started;
Player human;
Player enemy;
Ball ball;
mat4 viewProjection;
} State;
bool init(Game* game, State** pp_state) {
assert(game);
State* state = calloc(1, sizeof(State));
if (!state) {
return false;
}
*pp_state = state;
return true;
cleanup:
free(state);
return false;
}
void shutdown(Game* game, State* state) {
assert(game);
assert(state);
}
static void move_ball(Ball* ball, R dt, int width, int height) {
assert(ball);
const R offset = BALL_SIZE / 2;
ball->position = vec2_add(ball->position, vec2_scale(ball->velocity, dt));
// Right wall.
if (ball->position.x + offset > (R)width) {
ball->position.x = (R)width - offset - EPS;
ball->velocity.x = -ball->velocity.x;
}
// Left wall.
else if (ball->position.x - offset < 0) {
ball->position.x = offset + EPS;
ball->velocity.x = -ball->velocity.x;
}
// Top wall.
if (ball->position.y + offset > (R)height) {
ball->position.y = (R)height - offset - EPS;
ball->velocity.y = -ball->velocity.y;
}
// Bottom wall.
else if (ball->position.y - offset < 0) {
ball->position.y = offset + EPS;
ball->velocity.y = -ball->velocity.y;
}
}
void move_enemy_player(int width, Player* player, R t) {
const R half_width = (R)width / 2;
const R amplitude = half_width - (PAD_SIZE.x / 2);
player->position.x = half_width + amplitude * sinf(t * ENEMY_SPEED);
}
void move_human_player(Player* player, R dt) {
assert(player);
R speed = 0;
if (gfx_is_key_pressed('a')) {
speed -= PLAYER_SPEED;
}
if (gfx_is_key_pressed('d')) {
speed += PLAYER_SPEED;
}
player->position.x += speed * dt;
}
void clamp_player(Player* player, int width) {
assert(player);
const R offset = PAD_SIZE.x / 2;
// Left wall.
if (player->position.x + offset > (R)width) {
player->position.x = (R)width - offset;
}
// Right wall.
else if (player->position.x - offset < 0) {
player->position.x = offset;
}
}
void collide_ball(vec2 old_ball_position, const Player* player, Ball* ball) {
assert(player);
assert(ball);
// Discrete but simple collision. Checks for intersection and moves the ball
// back by a small epsilon.
// Player bounding box.
const vec2 player_pmin = vec2_make(
player->position.x - PAD_SIZE.x / 2, player->position.y - PAD_SIZE.y / 2);
const vec2 player_pmax = vec2_make(
player->position.x + PAD_SIZE.x / 2, player->position.y + PAD_SIZE.y / 2);
// Ball bounding box.
const vec2 ball_pmin = vec2_make(
ball->position.x - BALL_SIZE / 2, ball->position.y - BALL_SIZE / 2);
const vec2 ball_pmax = vec2_make(
ball->position.x + BALL_SIZE / 2, ball->position.y + BALL_SIZE / 2);
// Check for intersection and update ball.
if (!((ball_pmax.x < player_pmin.x) || (ball_pmin.x > player_pmax.x) ||
(ball_pmax.y < player_pmin.y) || (ball_pmin.y > player_pmax.y))) {
ball->position =
vec2_add(old_ball_position, vec2_scale(ball->velocity, -EPS));
ball->velocity.y = -ball->velocity.y;
}
}
void update(Game* game, State* state, double t, double dt) {
assert(game);
assert(state);
// TODO: Move game width/height to GfxApp query functions?
const vec2 old_ball_position = state->ball.position;
move_ball(&state->ball, (R)dt, game->width, game->height);
move_human_player(&state->human, (R)dt);
move_enemy_player(game->width, &state->enemy, (R)t);
clamp_player(&state->human, game->width);
collide_ball(old_ball_position, &state->human, &state->ball);
collide_ball(old_ball_position, &state->enemy, &state->ball);
}
static void draw_player(ImmRenderer* imm, const Player* player) {
assert(imm);
assert(player);
const vec2 half_box = vec2_div(PAD_SIZE, vec2_make(2, 2));
const vec2 pmin = vec2_sub(player->position, half_box);
const vec2 pmax = vec2_add(player->position, half_box);
const aabb2 box = aabb2_make(pmin, pmax);
gfx_imm_draw_aabb2(imm, box);
}
static void draw_ball(ImmRenderer* imm, const Ball* ball) {
assert(imm);
assert(ball);
const vec2 half_box = vec2_make(BALL_SIZE / 2, BALL_SIZE / 2);
const vec2 pmin = vec2_sub(ball->position, half_box);
const vec2 pmax = vec2_add(ball->position, half_box);
const aabb2 box = aabb2_make(pmin, pmax);
gfx_imm_draw_aabb2(imm, box);
}
void render(const Game* game, const State* state) {
assert(game);
assert(state);
ImmRenderer* imm = gfx_get_imm_renderer(game->gfx);
gfx_imm_start(imm);
gfx_imm_set_view_projection_matrix(imm, &state->viewProjection);
gfx_imm_load_identity(imm);
gfx_imm_set_colour(imm, vec4_make(1, 1, 1, 1));
draw_player(imm, &state->human);
draw_player(imm, &state->enemy);
draw_ball(imm, &state->ball);
gfx_imm_end(imm);
}
static R clamp_to_width(int width, R x, R extent) {
return min(x, (R)width - extent);
}
void resize(Game* game, State* state, int width, int height) {
assert(game);
assert(state);
state->viewProjection = mat4_ortho(0, (R)width, 0, (R)height, -1, 1);
state->human.position.y = PLAYER_Y_OFFSET;
state->enemy.position.y = (R)height - PLAYER_Y_OFFSET;
if (!state->game_started) {
state->human.position.x = (R)width / 2;
state->enemy.position.x = (R)width / 2;
state->ball.position =
vec2_div(vec2_make((R)width, (R)height), vec2_make(2, 2));
state->ball.velocity = vec2_make(BALL_SPEED, BALL_SPEED);
state->game_started = true;
} else {
state->human.position.x =
clamp_to_width(width, state->human.position.x, PAD_SIZE.x / 2);
state->enemy.position.x =
clamp_to_width(width, state->enemy.position.x, PAD_SIZE.x / 2);
}
}
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