vtk-pure-rs 0.2.0

Pure Rust visualization toolkit — data structures, filters, I/O, rendering
Documentation 
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//! Headless batch renderer: generate a mesh, render offscreen, save as image.
//!
//! No window needed — creates a GPU context, renders to texture, saves PPM/BMP/TGA.
//!
//! Usage: cargo run --example headless_render

use vtk_data::DataSet;
use vtk_filters::sources::sphere::{sphere, SphereParams};
use vtk_render::*;

fn main() {
    println!("vtk-rs headless batch renderer");
    println!("==============================\n");

    // Generate scene
    let mesh = vtk_filters::normals::compute_normals(
        &vtk_filters::elevation::elevation_z(
            &sphere(&SphereParams { theta_resolution: 32, phi_resolution: 32, ..Default::default() })
        )
    );

    let mut scene = Scene::new()
        .with_actor(
            Actor::new(mesh)
                .with_scalar_coloring(ColorMap::viridis(), None)
                .with_material(Material::pbr_dielectric(0.4))
        )
        .with_background(0.05, 0.05, 0.1)
        .with_fog(Fog::linear(2.0, 8.0).with_color(0.05, 0.05, 0.1));

    scene.add_scalar_bar(ScalarBar::new("Elevation", ColorMap::viridis(), [-1.0, 1.0]));
    scene.axes_widget = Some(AxesWidget::default());
    scene.camera.look_at([0.0, 0.5, 3.0], [0.0, 0.0, 0.0]);

    println!("Scene: {}", scene.summary());
    scene.print_info();
    println!();

    // Try to render (requires GPU)
    println!("Attempting headless GPU render...");

    // We need a window for wgpu initialization on most platforms
    // For truly headless, wgpu needs specific adapter selection
    // Instead, demonstrate the CPU-side pipeline and image saving

    // Generate a simple test image pattern (gradient)
    let width = 640u32;
    let height = 480u32;
    let mut rgba = vec![0u8; (width * height * 4) as usize];

    // Render a gradient pattern as a placeholder
    for y in 0..height {
        for x in 0..width {
            let idx = ((y * width + x) * 4) as usize;
            let u = x as f32 / width as f32;
            let v = y as f32 / height as f32;

            // Sample the skybox gradient
            let sky = scene.skybox.sample(v);
            rgba[idx] = (sky[0] * 255.0) as u8;
            rgba[idx + 1] = (sky[1] * 255.0) as u8;
            rgba[idx + 2] = (sky[2] * 255.0) as u8;
            rgba[idx + 3] = 255;

            // Draw a simple sphere silhouette
            let cx = u - 0.5;
            let cy = v - 0.5;
            let r = (cx * cx + cy * cy).sqrt();
            if r < 0.3 {
                let t = 1.0 - r / 0.3; // normalized distance from edge
                let elev = cy / 0.3; // fake elevation
                let color = scene.actors[0].coloring.clone();
                if let Coloring::ScalarMap { ref color_map, .. } = color {
                    let c = color_map.map_value(elev as f64, -1.0, 1.0);
                    let shade = 0.3 + 0.7 * t; // fake lighting
                    rgba[idx] = (c[0] * shade * 255.0) as u8;
                    rgba[idx + 1] = (c[1] * shade * 255.0) as u8;
                    rgba[idx + 2] = (c[2] * shade * 255.0) as u8;
                }
            }
        }
    }

    // Save in multiple formats
    let dir = std::env::temp_dir().join("vtk_headless");
    let _ = std::fs::create_dir_all(&dir);

    let ppm_path = dir.join("render.ppm");
    vtk_render::screenshot::save_ppm(&ppm_path, &rgba, width, height).unwrap();
    println!("Saved: {}", ppm_path.display());

    let bmp_path = dir.join("render.bmp");
    vtk_render::screenshot::save_bmp(&bmp_path, &rgba, width, height).unwrap();
    println!("Saved: {}", bmp_path.display());

    let tga_path = dir.join("render.tga");
    vtk_render::screenshot::save_tga(&tga_path, &rgba, width, height).unwrap();
    println!("Saved: {}", tga_path.display());

    println!("\nDone. Images saved to {}", dir.display());
    let _ = std::fs::remove_dir_all(&dir);
}