2.Output an Image

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "ray-trace-w1"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "ray-trace-w1"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/image.rs

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+/*
+* -------width(i)-------
+* |
+* |
+* height(j)
+* |
+* |
+* ----------------------
+* 
+* ppm p3 format:
+* 
+* P3
+* 
+* [width] [height]
+* [max color]
+* R1 G1 B1
+* R2 G2 B2
+* R3 G3 B3
+* ...xN
+*/
+pub fn gen_gradient_ppm_p3(width: i32, height: i32) -> String {
+    let mut img_content = format!("P3\n{} {}\n255\n", width, height);
+
+    for j in 0..height {
+        for i in 0..width {
+            let r = 256.0 * (i as f32 / (width-1) as f32);
+            let g = 256.0 * (j as f32 / (height-1) as f32);
+            let b = 256.0 * ((i+j) as f32 / (width + height - 2) as f32);
+
+            img_content.push_str(format!("{} {} {}", r as u8, g as u8, b as u8).as_str());
+            img_content.push('\n');
+        }
+    }
+
+    img_content
+}

src/main.rs

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+use write_file_util::{write_image};
+use image::{gen_gradient_ppm_p3};
+
+mod image;
+mod write_file_util;
+
+fn main() {
+    let ppm_content = gen_gradient_ppm_p3(400, 225);
+    write_image(ppm_content, "./target/test.ppm".to_string())
+}

src/write_file_util.rs

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+use std::{fs::File, io::{BufWriter, Write}};
+
+pub fn write_image(content: String, file_path: String) {
+    if let Ok(file) = File::create(file_path) {
+        let mut writer = BufWriter::new(file);
+        if let Err(e) = writer.write(content.as_bytes()) {
+            println!("写出失败：{:#}", e)
+        }
+    } else {
+        println!("PPM保存失败")
+    }
+}