upd simple shader

1 files changed, 17 insertions, 4 deletions

diff --git a/src/renderer.rs b/src/renderer.rs
index 3f94437..d27edb4 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -2,8 +2,17 @@ use crate::calculus::calculus::{Point3, Ray, Vec3};
 use crate::global::{Color, DisplayBuffer, Pixel, CAMERA_CENTER, FOCAL_LENGTH, IMG_HEIGHT, IMG_WIDTH, VIEWPORT_HEIGHT, VIEWPORT_WIDTH};
 
 fn ray_color(ray: &Ray) -> Color {
-    if hit_sphere(&Point3 {x: 0f32, y: 0f32, z: -1f32}, 0.5, ray) {
-        return Color {r: 1f32, g: 0f32, b: 0f32}
+    let t = hit_sphere(&Point3 {x: 0.0, y: 0.0, z: -1.0}, 0.5, ray);
+    if t > 0.0 {
+        let normal = ray
+            .at(t)
+            .sub(&Vec3 {x: 0.0, y: 0.0, z: -1.0})
+            .unit();
+        return Color::new(
+            normal.x + 1.0,
+            normal.y + 1.0,
+            normal.z + 1.0,
+        ).mul_scalar(0.5);
     }
     let unit_direction = ray.direction.unit();
     let a = 0.5 * (unit_direction.y + 1.0);
@@ -12,13 +21,17 @@ fn ray_color(ray: &Ray) -> Color {
     color1.add(&color2)
 }
 
-fn hit_sphere(center: &Point3, radius: f32, ray: &Ray) -> bool {
+fn hit_sphere(center: &Point3, radius: f32, ray: &Ray) -> f32 {
     let oc = center.sub(&ray.origin);
     let a = ray.direction.dot_prod(&ray.direction);
     let b = -2.0 * ray.direction.dot_prod(&oc);
     let c  = oc.dot_prod(&oc) - radius * radius;
     let discriminant = b * b - 4.0 * a * c;
-    discriminant >= 0.0
+    if discriminant < 0.0 {
+        -1.0
+    } else {
+        (-b - discriminant.sqrt()) / (2.0 * a)
+    }
 }
 
 pub fn render(display_buffer: &mut DisplayBuffer) {