From 0d2d5548aef7d63ffbc53a8f30f1900df4dd954f Mon Sep 17 00:00:00 2001
From: Kristofers Solo <kristians.cagulis@gmail.com>
Date: Tue, 30 Aug 2022 21:44:14 +0300
Subject: [PATCH] Fix flickering

---
 src/main.rs | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index a235030..c51587d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,11 +5,11 @@ fn main() {
     let mut a: f32 = 0.0;
     let mut b: f32 = 0.0;
 
-    print!("\x1B[2J"); // clears screen
+    print!("\x1b[2J"); // clears screen
 
     loop {
-        let mut z: [f32; SCREEN_SIZE] = [0.0; SCREEN_SIZE];
-        let mut screen: [char; SCREEN_SIZE] = [' '; SCREEN_SIZE];
+        let mut zbuffer: [f32; SCREEN_SIZE] = [0.0; SCREEN_SIZE];
+        let mut output: [char; SCREEN_SIZE] = [' '; SCREEN_SIZE];
 
         for j in (0..=628).step_by(7) {
             let j: f32 = 0.01 * j as f32;
@@ -28,16 +28,19 @@ fn main() {
                 let cos_j: f32 = j.cos();
 
                 let cos_j2: f32 = cos_j + 2.0;
-                let mess: f32 = 1.0 / (sin_i * cos_j2 * sin_a + sin_j * cos_a + 5.0);
+
+                let z: f32 = sin_i * cos_j2 * sin_a + sin_j * cos_a + 5.0;
+                let ooz: f32 = 1.0 / z; // one over z
+
                 let t: f32 = sin_i * cos_j2 * cos_a - sin_j * sin_a;
                 // 40 is the left screen shift
-                let x: i32 = (40.0 + 30.0 * mess * (cos_i * cos_j2 * cos_b - t * sin_b)) as i32;
+                let x: i32 = (40.0 + 30.0 * ooz * (cos_i * cos_j2 * cos_b - t * sin_b)) as i32;
                 // 12 is the bottom screen shift
-                let y: i32 = (12.0 + 15.0 * mess * (cos_i * cos_j2 * sin_b + t * cos_b)) as i32;
+                let y: i32 = (12.0 + 15.0 * ooz * (cos_i * cos_j2 * sin_b + t * cos_b)) as i32;
                 let o: usize = (x + WIDTH * y) as usize;
                 // multiplying by 8 to bring in range 0-11 as 8*(sqrt(2))=11
                 // because we have 11 luminance characters
-                let n: i32 = (8.0
+                let luminance_index: i32 = (8.0
                     * ((sin_j * sin_a - sin_i * cos_j * cos_a) * cos_b
                         - sin_i * cos_j * sin_a
                         - sin_j * cos_a
@@ -50,25 +53,25 @@ fn main() {
                 // i.e. when z[o] is 0 or the prev point is behind the new point
                 // so we change it to the point nearer to the eye/ above prev point
 
-                if 0 < y && y < HEIGHT && 0 < x && x < WIDTH && mess > z[o] {
-                    z[o] = mess;
-                    if n > 0 {
-                        let m: usize = n as usize;
-                        screen[o] = ".,-~:;=!*#$Q".chars().nth(m).unwrap();
+                if 0 < y && y < HEIGHT && 0 < x && x < WIDTH && ooz > zbuffer[o] {
+                    zbuffer[o] = ooz;
+                    if luminance_index > 0 {
+                        let m: usize = luminance_index as usize;
+                        output[o] = ".,-~:;=!*#$@".chars().nth(m).unwrap();
                     } else {
-                        screen[o] = '.';
+                        output[o] = '.';
                     }
                 }
             }
         }
         // print
-        print!("\x1B[2J");
-        for index in 0..screen.len() {
+        print!("\x1b[H");
+        for index in 0..output.len() {
             let i: i32 = index as i32;
             if i % WIDTH == 0 {
                 println!();
             } else {
-                print!("{}", screen[index]);
+                print!("{}", output[index]);
             }
         }