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// This file is part of ZiRC
//
// Copyright (C) 2021, tslil clingman
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
const std = @import("std");
const RenderWindow = @import("sfml").graphics.RenderWindow;
const Sprite = @import("sfml").graphics.Sprite;
usingnamespace @import("map.zig");
pub const RenderWallFunction: type = fn (
window: RenderWindow,
sprite: Sprite,
col: i32, // which column we're in
top: f32, // top of wall
draw_frac: f32,
length: f32, // length of slice to be drawn
texfrac: f32,
texture: u8, // which texture index
) void;
pub const Player = struct {
pos_x: f32,
pos_y: f32,
ang: f32,
vel_x: f32 = 0,
vel_y: f32 = 0,
acc_x: f32 = 0,
acc_y: f32 = 0,
fov: f32 = std.math.pi / 3.0,
height: f32 = 1.7, // TODO
plane_height: f32,
plane_width: i32,
plane_dist: f32,
pub fn new(pos_x: f32, pos_y: f32, ang: f32, plane_width: i32, plane_height: i32) Player {
const fov: f32 = std.math.pi / 3.0;
return Player{
// standing still at the given location, looking in direction ang,
.pos_x = pos_x,
.pos_y = pos_y,
.ang = ang,
// plane of projection
.plane_width = plane_width,
.plane_height = @intToFloat(f32, plane_height),
// given the desired width of the image, how far away must
// the projection plane be from the camera?
.plane_dist = @intToFloat(f32, plane_width) / (2 * std.math.tan(fov / 2)),
};
}
pub fn tick(self: *Player) void {
const dt = 1 / 30.0;
const v_min = 0.8;
const v_decay = 1.25;
self.pos_x += self.vel_x * dt;
self.pos_y += self.vel_y * dt;
self.vel_x /= v_decay;
if (std.math.fabs(self.vel_x) < v_min) self.vel_x = 0;
self.vel_y /= v_decay;
if (std.math.fabs(self.vel_y) < v_min) self.vel_y = 0;
self.vel_x += self.acc_x * dt;
self.vel_y += self.acc_y * dt;
}
pub fn renderMapUsing(
self: Player,
window: RenderWindow,
sprite: Sprite,
map: Map,
// the abstract the rendering call
renderWall: RenderWallFunction,
) void {
const floor = std.math.floor;
var col: i32 = 0;
while (col < self.plane_width) : (col += 1) {
const horiz_frac = @intToFloat(f32, col) / (@intToFloat(f32, self.plane_width) - 1);
const ra = (0.5 - horiz_frac) * self.fov + self.ang;
const cosra = std.math.cos(ra);
const sinra = std.math.sin(ra);
// Observe that sqrt(1+tan^2) = abs(1/cos) sqrt(cos^2+sin^2) =
// abs(1/cos). Similarly so for cot, hence we obtain the following
// lengths for the hypotenuses assuming that x (respectively y) are
// unit length and the angle is ra.
const dy_for_x_step = std.math.fabs(1 / cosra);
const dx_for_y_step = std.math.fabs(1 / sinra);
var step_x: i32 = -1;
var step_y: i32 = -1;
var dist_x: f32 = undefined;
var dist_y: f32 = undefined;
var ipos_x: i32 = @floatToInt(i32, floor(self.pos_x));
var ipos_y: i32 = @floatToInt(i32, floor(self.pos_y));
// looking right
if (cosra >= 0) {
step_x = 1;
// assuming unit size grid cells
dist_y = (@intToFloat(f32, ipos_x) + 1 - self.pos_x) * dy_for_x_step;
} else {
dist_y = (self.pos_x - @intToFloat(f32, ipos_x)) * dy_for_x_step;
}
if (sinra >= 0) {
step_y = 1;
dist_x = (@intToFloat(f32, ipos_y) + 1 - self.pos_y) * dx_for_y_step;
} else {
dist_x = (self.pos_y - @intToFloat(f32, ipos_y)) * dx_for_y_step;
}
var distance: f32 = 0;
var still_drawing = true;
var highest_point: f32 = 0;
var horizontal_hit: bool = undefined;
while (still_drawing) {
// Find the next cell on our path
if (dist_y < dist_x) {
horizontal_hit = false;
distance = dist_y;
dist_y += dy_for_x_step;
ipos_x += step_x;
} else {
horizontal_hit = true;
distance = dist_x;
dist_x += dx_for_y_step;
ipos_y += step_y;
}
if (!map.inBounds(ipos_x, ipos_y)) break;
var cell = map.lookup(ipos_x, ipos_y);
// the correct distance is the shortest distance from the plane
// of projection to the point, that is, perpendicular distance
const perp_distance = distance * std.math.cos(self.ang - ra);
// project the top of the wall
const top = self.plane_height / 2 + self.plane_dist * (cell.height - self.height) / perp_distance;
// We have a wall to draw if it protrudes above what we have so far drawn
if (top > highest_point) {
// did we extend beyond the top of the plane?
if (top > self.plane_height) still_drawing = false;
// compute the height of this wall
const total_length = self.plane_dist * cell.height / perp_distance;
// as well as the fraction we'll be drawing
const draw_frac = std.math.min(1, (top - highest_point) / total_length);
// we need the raw Euclidean distance to calculate the
// fractional part of the relevant coordinate for texture
// mapping of the walls
const hit_coordinate = if (horizontal_hit) distance * cosra + self.pos_x else distance * sinra + self.pos_y;
var texfrac = std.math.modf(hit_coordinate).fpart;
// we also want to be sure that we're consistently orienting
// textures, in this case clockwise
if ((horizontal_hit and sinra < 0) or (!horizontal_hit and cosra > 0)) texfrac = 1 - texfrac;
renderWall(window, sprite, col, top, total_length, draw_frac, texfrac, cell.wall_texture);
highest_point = top;
}
}
}
}
};
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