zig-learn/primitives.zig

const std = @import("std");
const term = @import("term.zig");
const Winsize = term.Winsize;

pub const Direction = struct {
    x: i8 = 1,
    y: i8 = 1,
    z: i8 = 1,
};
pub const Point = struct {
    x: i32 = 0,
    y: i32 = 0,
    z: i32 = 0,
    direction: Direction, //for movement state
};
pub const Vec3 = struct {
    a: Point = .{ .x = 0, .y = 0, .z = 0, .direction = .{ .x = 0, .y = 0, .z = 0 } },
    b: Point = .{ .x = 0, .y = 0, .z = 0, .direction = .{ .x = 0, .y = 0, .z = 0 } },
    c: Point = .{ .x = 0, .y = 0, .z = 0, .direction = .{ .x = 0, .y = 0, .z = 0 } },
};
pub const Triangle = struct {
    bufa: *i32,
    bufb: *i32,
    bufc: *i32,
};

pub fn pixel(buffer: []u8, w: Winsize, x: i64, y: i64, symbol: u21) !void {
    const i: usize = @intCast(4 * (x + y * w.ws_col));
    if (i < buffer.len) { //-1 ??
        const slice = buffer[i .. i + 4];
        _ = try std.unicode.utf8Encode(symbol, slice);
        //TODO: check length, set not used bytes to zero
    } else {
        //print("Error illegal memory access\n", .{});
    }
}
pub fn bresenham(buf: []u8, w: Winsize, p1: Point, p2: Point) !void {
    var x: i32 = p1.x;
    var y: i32 = p1.y;
    const dx = (p2.x - p1.x);
    const dy = (p2.y - p1.y);
    var er: i64 = 0;
    if (dx >= dy and dy > 0 and dx > 0) {
        while (x <= p2.x) : (x += 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += dy;
            if (2 * er >= dx) {
                y += 1;
                er -= dx;
            }
        }
    } else if (dx <= dy and dy >= 0 and dx >= 0) {
        while (y <= p2.y) : (y += 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += dx;
            if (2 * er >= dy) {
                x += 1;
                er -= dy;
            }
        }
    } else if (@abs(dy) <= dx and dy <= 0 and dx >= 0) {
        while (x <= p2.x) : (x += 1) {
            _ = try pixel(buf, w, x, y, '█');
            er -= dy;
            if (2 * er >= dx) {
                y -= 1;
                er -= dx;
            }
        }
    } else if (@abs(dy) >= dx and dy <= 0 and dx >= 0) {
        while (y >= p2.y) : (y -= 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += dx;
            if (2 * er >= dy) {
                x += 1;
                er += dy;
            }
        }
    } else if (@abs(dx) <= dy and dx <= 0 and dy >= 0) {
        while (y <= p2.y) : (y += 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += @abs(dx);
            if (2 * er >= dy) {
                x -= 1;
                er -= dy;
            }
        }
    } else if (@abs(dx) >= dy and dy >= 0 and dx <= 0) {
        while (x >= p2.x) : (x -= 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += dy;
            if (2 * er >= @abs(dx)) {
                y += 1;
                er -= @abs(dx);
            }
        }
    } else if (dx <= dy and dx <= 0 and dy <= 0) {
        while (x >= p2.x) : (x -= 1) {
            _ = try pixel(buf, w, x, y, '█');
            er += @abs(dy);
            if (2 * er >= @abs(dx)) {
                y -= 1;
                er -= @abs(dx);
            }
        }
    } else if (dx >= dy and dy <= 0 and dx <= 0) {
        while (y >= p2.y) : (y -= 1) {
            //print("x:{},y:{},er:{},dx:{},dy:{}\n", .{ x, y, er, dx, dy });
            _ = try pixel(buf, w, x, y, '█');
            er += @abs(dx);
            if (2 * er >= @abs(dx)) {
                x -= 1;
                er -= @abs(dy);
            }
        }
    }
}
pub fn triangle(buffer: []u8, w: Winsize, vector: Vec3) !void {
    try bresenham(buffer, w, vector.a, vector.b);
    try bresenham(buffer, w, vector.b, vector.c);
    try bresenham(buffer, w, vector.c, vector.a);
}