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const std = @import("std");
const graphics = @import("root.zig");
pub const Line = struct {
const Self = @This();
const Point = struct {
x: u32,
y: u32,
};
start: Point,
end: Point,
color: graphics.Color,
fn distance(a: u32, b: u32) u32 {
if (a < b) {
return b - a;
} else {
return a - b;
}
}
pub fn render(self: *const Self, canvas: *const graphics.Canvas) void {
var start = self.start;
var end = self.end;
const steep = distance(start.y, end.y) > distance(start.x, end.x);
if (steep) {
std.mem.swap(u32, &start.x, &start.y);
std.mem.swap(u32, &end.x, &end.y);
}
if (start.x > end.x) {
std.mem.swap(Point, &start, &end);
}
const dx: f64 = @floatFromInt(end.x - start.x);
const dy: f64 = @floatFromInt(@as(i64, @intCast(end.y)) - @as(i64, @intCast(start.y)));
var gradient: f64 = dy / dx;
if (dx == 0) {
gradient = 1;
}
var intersect_y: f64 = @floatFromInt(start.y);
if (steep) {
for (start.x..end.x + 1) |x| {
const y: u64 = @intFromFloat(intersect_y);
const factor = intersect_y - @as(f64, @floatFromInt(y));
var previous_color = canvas.buffer[x * canvas.width + y];
canvas.buffer[x * canvas.width + y] = self.color.mix(&previous_color, factor);
previous_color = canvas.buffer[canvas.width * x + y + 1];
canvas.buffer[x * canvas.width + y + 1] = previous_color.mix(&self.color, factor);
intersect_y += gradient;
}
} else {
for (start.x..end.x + 1) |x| {
const y: u64 = @intFromFloat(intersect_y);
const factor = intersect_y - @as(f64, @floatFromInt(y));
var previous_color = canvas.buffer[x + canvas.width * y];
canvas.buffer[x + canvas.width * y] = self.color.mix(&previous_color, factor);
previous_color = canvas.buffer[x + canvas.width * (y + 1)];
canvas.buffer[x + canvas.width * (y + 1)] = previous_color.mix(&self.color, factor);
intersect_y += gradient;
}
}
}
};
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