From 3d835bcf631ebc1407671fdf153a35d4c1944038 Mon Sep 17 00:00:00 2001 From: dqn Date: Sat, 2 Aug 2025 02:35:31 +0800 Subject: [PATCH] 6.1/6.1.Shading with Surface Normals --- src/image.rs | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++- src/main.rs | 40 +++++++++++++++++++++++++- 2 files changed, 117 insertions(+), 2 deletions(-) diff --git a/src/image.rs b/src/image.rs index cb0df1f..d81da7e 100644 --- a/src/image.rs +++ b/src/image.rs @@ -10,6 +10,41 @@ impl Color { } } +pub fn gen_ray_sphere_normal_ppm_p3(width: i32, height: i32, camera_center: Vec3, viewport_top_left_pixel_center: Vec3, viewport_u_delta: Vec3, viewport_v_delta: Vec3) -> String { + let mut img_content = format!("P3\n{} {}\n255\n", width, height); + + for j in 0..height { + + if j % 10 == 0 { + println!("scan line {}/{} ", j + 1, height); + } + + for i in 0..width { + // every pixcel's position + let pixel_center = viewport_top_left_pixel_center + (i as f32 * viewport_u_delta) + (j as f32 * viewport_v_delta); + // Vector(camera, pixcel) + let ray_direction = pixel_center - camera_center; + // ray + let r = Ray::new(camera_center, ray_direction); + + /* + 球 + */ + let _sphere_center = Point::new(0.0, 0.0, -1.0); + let sphere_radius = 0.5; + + // determind color + let color = ray_color_at_sphere_normal(&r, _sphere_center, sphere_radius); + // content + img_content.push_str(color.to_color().as_str()); + img_content.push('\n'); + } + } + + img_content +} + + pub fn gen_ray_sphere_ppm_p3(width: i32, height: i32, camera_center: Vec3, viewport_top_left_pixel_center: Vec3, viewport_u_delta: Vec3, viewport_v_delta: Vec3) -> String { let mut img_content = format!("P3\n{} {}\n255\n", width, height); @@ -85,9 +120,51 @@ fn hit_sphere(r: &Ray, sphere_center: Point, sphere_radius: f32) -> bool { } +fn hit_sphere_normal(r: &Ray, sphere_center: Point, sphere_radius: f32) -> f32 { + let a: f32 = r.direction.length_squared(); + let h = r.direction.dot(sphere_center - r.point); + // let b = -2.0 * r.direction.dot(sphere_center - r.point); + let c = (sphere_center - r.point).length_squared() - sphere_radius * sphere_radius; + + let discriminant = h*h - a*c; + + // // 两个焦点 + let disc_sqrt = discriminant.sqrt(); + let near = (h - disc_sqrt) / a; + let far = (h + disc_sqrt) / a; + + // 射线起点可能在球内的情况 + if near >= 0.0 && far >= 0.0 { + return near.min(far); + } else if near > 0.0 { + return near; + } else if far > 0.0 { + return far; + } else { + return -1.0 + } +} + /* -get color of this ray; background +ray color functions */ +fn ray_color_at_sphere_normal(r: &Ray, sphere_center: Point, sphere_radius: f32) -> Color { + + let t = hit_sphere_normal(r, sphere_center, sphere_radius); + if t >= 0.0 { + let inter_point = r.at(t); + // 单位向量 + let n = inter_point / inter_point.dot(inter_point); + // 法向量也是 -1～1 +1再x0.5让他落到颜色的区间 + return 0.5 * (n - sphere_center + Point::new(1.0, 1.0, 1.0)) + } + + // v / |v| + let unit_direction = r.direction / r.direction.length(); + let a = 0.5*(unit_direction.y + 1.0); + return (1.0-a)*Color::new(1.0, 1.0, 1.0) + a*Color::new(0.5, 0.7, 1.0); +} + fn ray_color_at_sphere(r: &Ray, sphere_center: Point, sphere_radius: f32) -> Color { // return RED if hit sphere diff --git a/src/main.rs b/src/main.rs index 1f63241..2c5784f 100644 --- a/src/main.rs +++ b/src/main.rs @@ -4,7 +4,7 @@ use vec3::{Vec3}; use point::{Point}; use ray::{Ray}; -use crate::image::gen_ray_sphere_ppm_p3; +use crate::image::{gen_ray_sphere_normal_ppm_p3, gen_ray_sphere_ppm_p3}; mod image; mod write_file_util; @@ -19,9 +19,47 @@ fn main() { println!("=================================="); ray_sphere_scene_render(); println!("=================================="); + ray_sphere_normal_scene_render(); + println!("=================================="); } +fn ray_sphere_normal_scene_render() { + let aspect_ratio = 16.0/9.0; + let image_width = 400; + // aleast 1px + let image_height = ((image_width as f32 / aspect_ratio) as i32).max(1); + + let viewport_height = 2.0; + let viewport_width = viewport_height * (image_width as f32 / image_height as f32); + + println!("set image({},{}), viewport({},{})", image_width, image_height, viewport_width, viewport_height); + let viewport_u = Vec3::new(viewport_width, 0.0, 0.0); + // image x--> right + // | + // y + // space: y up , x right , z back, -z front + let viewport_v = Vec3::new(0.0, -viewport_height, 0.0); + + // width per pix + let viewport_u_delta = viewport_u / (image_width as f32); + // height per pix + let viewport_v_delta = viewport_v / (image_height as f32); + + // camerea position + let camera_center = Point::new(0.0, 0.0, 0.0); + // -z 1.0 viewport to camera + let focal_length = Vec3::new(0.0, 0.0, -1.0); + // camera position --> viewport center ---> top center --> top left + let viewport_top_left_pixel = camera_center + focal_length - viewport_u / 2.0 - viewport_v / 2.0; + // padding 0.5* delta u/v + let viewport_top_left_pixel_center = viewport_top_left_pixel - viewport_u_delta / 2.0 - viewport_v_delta / 2.0; + + let ppm_content = gen_ray_sphere_normal_ppm_p3(image_width, image_height, camera_center, viewport_top_left_pixel_center, viewport_u_delta, viewport_v_delta); + + write_image(ppm_content, "./target/ray_sphere_normal_scene_render.ppm".to_string()) +} + fn ray_sphere_scene_render() { let aspect_ratio = 16.0/9.0; let image_width = 400;