78 lines
2.6 KiB
Zig
78 lines
2.6 KiB
Zig
const std = @import("std");
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const color = @import("./color.zig");
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const ray = @import("./ray.zig");
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const vec = @import("./vec.zig");
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const Color = vec.Color;
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const Vec3 = vec.Vec3;
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const Point3 = vec.Point3;
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const info = std.log.info;
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const write_color = color.write_color;
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const Ray = ray.Ray;
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fn hit_sphere(center: Point3, radius: f32, r: Ray) f32 {
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const oc = r.origin().sub(center);
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const a = Vec3.dot(r.direction(), r.direction());
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const b = Vec3.dot(oc, r.direction()) * 2;
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const c = Vec3.dot(oc, oc) - radius * radius;
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const discriminant = b * b - 4 * a * c;
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return if (discriminant < 0) -1 else (-b - @sqrt(discriminant)) / (2 * a);
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}
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fn ray_color(r: Ray) Color {
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var t = hit_sphere(Point3.init(0, 0, -1), 0.5, r);
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if (t > 0) {
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const n = r.at(t).sub(Vec3.init(0, 0, -1)).unit();
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return Color.init(
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n.x() + 1,
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n.y() + 1,
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n.z() + 1,
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).scale(0.5);
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}
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var unit_direction = r.direction().unit();
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t = 0.5 * (unit_direction.y() + 1);
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return Color.init(1, 1, 1).scale(1 - t).add(Color.init(0.5, 0.7, 1.0).scale(t));
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}
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pub fn main() anyerror!void {
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// Image
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const aspect_ratio: f32 = 16.0 / 9.0;
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const image_width = 400;
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const image_height = @floatToInt(isize, @intToFloat(f32, image_width) / aspect_ratio);
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// Camera
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const viewport_height = 2;
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const viewport_width = aspect_ratio * viewport_height;
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const focal_length = 1;
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const origin = Point3.init(0, 0, 0);
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const horizontal = Vec3.init(viewport_width, 0, 0);
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const vertical = Vec3.init(0, viewport_height, 0);
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const lower_left_corner = origin.sub(horizontal.scale(0.5)).sub(vertical.scale(0.5)).sub(Vec3.init(0, 0, focal_length));
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const stdout = std.io.getStdOut();
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info("Writing image {d}x{d}", .{ image_width, image_height });
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try stdout.writer().print("P3\n{d} {d}\n255\n", .{ image_width, image_height });
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var j: isize = image_height - 1;
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while (j >= 0) : (j -= 1) {
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//info("Scanlines remaining: {d}", .{j});
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var i: isize = 0;
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while (i < image_width) : (i += 1) {
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const u = @intToFloat(f32, i) / @intToFloat(f32, image_width - 1);
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const v = @intToFloat(f32, j) / @intToFloat(f32, image_height - 1);
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const r = Ray.init(origin, lower_left_corner.add(horizontal.scale(u)).add(vertical.scale(v)).sub(origin));
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const pixel_color = ray_color(r);
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try write_color(pixel_color);
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}
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}
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info("Done", .{});
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}
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test {
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// Run tests in imported source.
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std.testing.refAllDecls(@This());
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}
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