OneCAD/crates/engine/src/view.rs

//! What the viewport shows, independent of the UI toolkit: body meshes, edges, sketches, the
//! grid and the origin. Used by the headless snapshot renderer; the GPU viewport draws the same
//! content.

use std::sync::Arc;

use solidcraft_geom::{Aabb3, Plane, Vec3};
use solidcraft_render::{Camera, Rgb, Scene, SceneLine, SceneMesh};
use solidcraft_sketch::Sketch;

use crate::{Sel, Session};

/// Colours (shared with the GPU viewport).
pub mod colors {
    use solidcraft_render::Rgb;
    pub const BODY: Rgb = Rgb(176, 186, 198);
    pub const BODY_SELECTED: Rgb = Rgb(110, 170, 235);
    pub const EDGE: Rgb = Rgb(40, 44, 52);
    pub const SKETCH: Rgb = Rgb(30, 90, 200);
    pub const SKETCH_DONE: Rgb = Rgb(20, 20, 20);
    pub const SKETCH_CONSTRUCTION: Rgb = Rgb(230, 130, 40);
    pub const SKETCH_FIXED: Rgb = Rgb(20, 20, 20);
    /// Fixed (locked) geometry.
    pub const SKETCH_LOCKED: Rgb = Rgb(0, 140, 60);
    pub const SKETCH_CENTERLINE: Rgb = Rgb(200, 110, 60);
    /// Linked (projected) reference geometry.
    pub const SKETCH_PROJECTED: Rgb = Rgb(150, 60, 190);
    /// Linked geometry whose reference was lost.
    pub const SKETCH_LOST: Rgb = Rgb(200, 60, 90);
    pub const PROFILE: Rgb = Rgb(255, 196, 120);
    pub const GRID: Rgb = Rgb(196, 202, 212);
    pub const GRID_MAJOR: Rgb = Rgb(170, 178, 190);
    pub const AXIS_X: Rgb = Rgb(220, 60, 60);
    pub const AXIS_Y: Rgb = Rgb(60, 170, 60);
    pub const AXIS_Z: Rgb = Rgb(60, 100, 230);
    pub const BG_TOP: Rgb = Rgb(240, 243, 247);
    pub const BG_BOTTOM: Rgb = Rgb(203, 210, 221);
    /// What the section cap is tinted toward.
    pub const SECTION_CAP: Rgb = solidcraft_render::SECTION_CAP;
}

/// Bounds of everything visible now, in world space: shown bodies where their occurrences,
/// joints and moves place them, and the sketches the view draws (not ones used by a feature,
/// hidden ones, or ones in hidden components). What Home, Fit and the orbit pivot frame.
pub fn bounds(s: &Session) -> Aabb3 {
    visible_bounds(s, true)
}

/// [`bounds`], with the browser's Sketches folder shown (`sketches`) or hidden.
pub fn visible_bounds(s: &Session, sketches: bool) -> Aabb3 {
    let st = s.world_state();
    let mut b = Aabb3::EMPTY;
    for body in st.bodies.iter().filter(|x| s.body_visible(&x.name)) {
        b = b.union(&body.mesh().bounds());
    }
    for ss in st.sketches.iter().filter(|x| sketch_drawn(s, x.feature, sketches)) {
        // All four corners: on a tilted plane two opposite ones don't span the rectangle.
        if let Some((lo, hi)) = ss.sketch.bounds() {
            for p in [lo, hi, solidcraft_geom::Vec2::new(lo.x, hi.y), solidcraft_geom::Vec2::new(hi.x, lo.y)] {
                b.add(ss.plane.to_world(p));
            }
        }
        for w in ss.sketch.wires.iter().filter(|w| !w.fit.is_empty() || !ss.sketch.view.hide_projected) {
            for p in &w.pts {
                b.add(*p);
            }
        }
    }
    b
}

/// Grid spacing (minor, major) for a view of the given half height.
pub fn grid_step(half_height: f64) -> (f64, f64) {
    let raw = (half_height / 10.0).max(1e-3);
    let p = 10f64.powf(raw.log10().floor());
    let minor = if raw / p < 2.0 {
        p
    } else if raw / p < 5.0 {
        2.0 * p
    } else {
        5.0 * p
    };
    (minor, minor * 5.0)
}

/// Sketch curves as world polylines with their colour.
pub fn sketch_lines(sk: &Sketch, plane: &Plane, active: bool, determined: &[bool]) -> Vec<(Vec<Vec3>, Rgb, bool)> {
    sketch_lines_with_sampler(sk, plane, active, determined, world_curve_parts)
}

fn world_curve_parts(sk: &Sketch, i: usize, plane: &Plane) -> Vec<Vec<Vec3>> {
    sk.segs(i).into_iter().map(|seg| seg.polyline(0.02).iter().map(|p| plane.to_world(*p)).collect()).collect()
}

/// Sketch display paths with the same visibility and styling as [`sketch_lines`].
///
/// The sampler receives each visible 2D curve once and returns world-coordinate
/// parts. Parts remain separate, so a view-dependent sampler can leave clipping
/// gaps without drawing a line across them. Already placed 3D wires retain their
/// existing paths. Sampling changes only display geometry, never the sketch.
pub fn sketch_lines_with_sampler(
    sk: &Sketch,
    plane: &Plane,
    active: bool,
    determined: &[bool],
    mut sampler: impl FnMut(&Sketch, usize, &Plane) -> Vec<Vec<Vec3>>,
) -> Vec<(Vec<Vec3>, Rgb, bool)> {
    let mut out = Vec::new();
    for (i, c) in sk.curves.iter().enumerate() {
        if !sketch_curve_visible(sk, i) {
            continue;
        }
        let col = if c.link.is_some() && !sk.is_text_curve(i) {
            if sk.is_lost_curve(i) { colors::SKETCH_LOST } else { colors::SKETCH_PROJECTED }
        } else if c.fixed {
            colors::SKETCH_LOCKED
        } else if c.centerline {
            colors::SKETCH_CENTERLINE
        } else if c.construction {
            colors::SKETCH_CONSTRUCTION
        } else if !active {
            colors::SKETCH_DONE
        } else if determined.get(i).copied().unwrap_or(false) {
            colors::SKETCH_FIXED
        } else {
            colors::SKETCH
        };
        for part in sampler(sk, i, plane) {
            out.push((part, col, c.construction || c.centerline));
        }
    }
    // Virtual sharp corners (kept by fillets and chamfers): thin extension lines from the
    // curves to the corner, like construction geometry.
    for (_, ext) in sk.virtual_corners() {
        for (a, b) in ext {
            out.push((vec![plane.to_world(a), plane.to_world(b)], colors::SKETCH_CONSTRUCTION, true));
        }
    }
    // 3D curves are in world coordinates already.
    for w in sk.wires.iter().filter(|w| !w.fit.is_empty() || !sk.view.hide_projected) {
        // Curves drawn in a 3D sketch look like the sketch's own; included ones are references.
        let col = if w.fit.is_empty() {
            colors::SKETCH_PROJECTED
        } else if active {
            colors::SKETCH
        } else {
            colors::SKETCH_DONE
        };
        out.push((w.pts.clone(), col, false));
    }
    out
}

/// Should sketch curve `i` be drawn and picked? The Sketch Palette's two geometry toggles each
/// hide one category, and a curve belongs to the category its colour already names in
/// [`sketch_lines_with_sampler`]: a linked curve is projected reference geometry (Projected
/// Geometries), anything else carrying the `construction` line type is construction geometry
/// (Construction Geometries). Text outlines are linked curves that the Text feature draws, so
/// they are never reference geometry and always show. Centerlines are their own line type and
/// no toggle hides them.
///
/// Drawing and picking share this one answer so they cannot drift: geometry that is not on
/// screen is never clickable, and geometry on screen always is.
pub fn sketch_curve_visible(sk: &Sketch, i: usize) -> bool {
    let Some(c) = sk.curves.get(i) else { return false };
    if c.link.is_some() && !sk.is_text_curve(i) {
        return !sk.view.hide_projected;
    }
    !(c.construction && sk.view.hide_construction)
}

/// Should sketch point `i` be drawn? Text outlines' points are not (they are not picked or
/// constrained individually).
pub fn sketch_point_visible(sk: &Sketch, i: usize) -> bool {
    match sk.points.get(i).and_then(|p| p.link.as_deref()) {
        Some(l) => sk.link(l).is_none_or(|l| l.kind != solidcraft_sketch::LinkKind::Text),
        None => true,
    }
}

/// The scene for a headless render, cut by the session's section.
pub fn scene(s: &Session, cam: &Camera) -> Scene {
    scene_with_section(s, cam, s.section)
}

/// The scene for a headless render, cut by `section` (origin, normal) instead of the session's:
/// the app passes the cut its viewport shows (an open Section Analysis dialog's preview, a
/// sketch's Slice), so model renders match the window.
pub fn scene_with_section(s: &Session, cam: &Camera, section: Option<(Vec3, Vec3)>) -> Scene {
    scene_with_section_and_sketch_sampler(s, cam, section, world_curve_parts)
}

/// A headless scene using supplied display paths for its visible sketch curves.
/// Callers can use the same pixel sampler as a GPU viewport without changing the
/// body, grid, appearance, section or sketch styling policies of [`scene`].
pub fn scene_with_sketch_sampler(s: &Session, cam: &Camera, sampler: impl FnMut(&Sketch, usize, &Plane) -> Vec<Vec<Vec3>>) -> Scene {
    scene_with_section_and_sketch_sampler(s, cam, s.section, sampler)
}

/// A headless scene with an explicit section and supplied sketch display paths.
pub fn scene_with_section_and_sketch_sampler(
    s: &Session,
    cam: &Camera,
    section: Option<(Vec3, Vec3)>,
    mut sampler: impl FnMut(&Sketch, usize, &Plane) -> Vec<Vec<Vec3>>,
) -> Scene {
    let st = s.world_state();
    let section = section.filter(|(o, n)| o.is_finite() && n.is_finite() && n.len() > 1e-9);
    let mut sc = Scene {
        background: Some((colors::BG_TOP, colors::BG_BOTTOM)),
        clip: section.map(|(o, n)| (n, n.dot(o))),
        cap: Some(colors::SECTION_CAP),
        ..Default::default()
    };
    let b = bounds(s);
    sc.radius = (b.diagonal() * 0.5).max(cam.half_height()).max(10.0) + b.center().dist(cam.target);
    // Grid on the ground plane (XY with Z up, XZ with Y up).
    let (minor, major) = grid_step(cam.half_height());
    let ext = (cam.half_height() * 3.0 / major).ceil() * major;
    let tf = cam.to_frame(cam.target);
    let c = Vec3::new((tf.x / major).round() * major, (tf.y / major).round() * major, 0.0);
    let w = |p: Vec3| cam.from_frame(p);
    let n = ((ext / minor) as i64).clamp(1, 400);
    for i in -n..=n {
        let t = i as f64 * minor;
        let col = if (t / major).fract().abs() < 1e-9 { colors::GRID_MAJOR } else { colors::GRID };
        sc.lines.push(SceneLine {
            points: vec![w(c + Vec3::new(t, -ext, 0.0)), w(c + Vec3::new(t, ext, 0.0))],
            color: col,
            width: 0.6,
            on_top: false,
        });
        sc.lines.push(SceneLine {
            points: vec![w(c + Vec3::new(-ext, t, 0.0)), w(c + Vec3::new(ext, t, 0.0))],
            color: col,
            width: 0.6,
            on_top: false,
        });
    }
    let axis = cam.half_height() * 0.25;
    for (d, col) in [(Vec3::X, colors::AXIS_X), (Vec3::Y, colors::AXIS_Y), (Vec3::Z, colors::AXIS_Z)] {
        sc.lines.push(SceneLine { points: vec![Vec3::ZERO, d * axis], color: col, width: 1.6, on_top: false });
    }
    let selected_occurrences: Vec<String> = s
        .selection
        .iter()
        .filter_map(|x| match x {
            Sel::Occurrence { path } => s.occurrence_bodies(path, true).ok(),
            _ => None,
        })
        .flatten()
        .collect();
    for body in st.bodies.iter().filter(|b| s.body_visible(&b.name)) {
        let selected = selected_occurrences.contains(&body.name) || s.selection.iter().any(|x| matches!(x, Sel::Body { name } if *name == body.name));
        let mesh = body.mesh();
        // The body's appearance (or imported colour) and faces with looks of their own, as in
        // the viewport.
        let to8 = |x: f32| (x.clamp(0.0, 1.0) * 255.0).round() as u8;
        let color =
            if selected { colors::BODY_SELECTED } else { s.doc.body_color(body).map_or(colors::BODY, |[r, g, b]| Rgb(to8(r), to8(g), to8(b))) };
        let face_colors = if selected {
            Vec::new()
        } else {
            s.doc.face_colors(body).into_iter().map(|(f, l)| (f as u32, Rgb(l.color[0], l.color[1], l.color[2]))).collect()
        };
        sc.meshes.push(SceneMesh { mesh: Arc::clone(&mesh), color, face_colors });
        for (i, e) in mesh.edges.iter().enumerate() {
            if !mesh.shaded_edge_visible(i) {
                continue;
            }
            sc.lines.push(SceneLine { points: e.clone(), color: colors::EDGE, width: 1.2, on_top: false });
        }
        // The outline of the body where the section cuts it.
        if let Some((o, n)) = section {
            for (a, b) in section_segments(&mesh, o, n) {
                sc.lines.push(SceneLine { points: vec![a, b], color: colors::EDGE, width: 1.6, on_top: false });
            }
        }
    }
    for ss in &st.sketches {
        let active = s.active_sketch == Some(ss.feature);
        if !sketch_shown(s, ss.feature) {
            continue;
        }
        for (pts, col, cons) in sketch_lines_with_sampler(&ss.sketch, &ss.plane, active, &ss.report.curve_determined, &mut sampler) {
            sc.lines.push(SceneLine { points: pts, color: col, width: if cons { 1.0 } else { 1.6 }, on_top: active });
        }
    }
    sc
}

/// Where the plane through `o` with normal `n` cuts a mesh: one segment per crossed triangle,
/// nudged a hair to the kept side (so the clip leaves them drawn).
pub fn section_segments(m: &solidcraft_geom::Mesh, o: Vec3, n: Vec3) -> Vec<(Vec3, Vec3)> {
    let eps = 1e-4 * (1.0 + m.bounds().diagonal());
    let mut out = Vec::new();
    for t in &m.triangles {
        let Some(p) = m.tri(t) else { continue };
        let d = p.map(|q| n.dot(q - o));
        let mut pts = Vec::with_capacity(2);
        for (i, j) in [(0, 1), (1, 2), (2, 0)] {
            if (d[i] < 0.0) != (d[j] < 0.0) {
                let s = d[i] / (d[i] - d[j]);
                pts.push(p[i] + (p[j] - p[i]) * s - n * eps);
            }
        }
        if let [a, b] = pts[..] {
            out.push((a, b));
        }
    }
    out
}

/// Is a sketch drawn? The active one is; others unless hidden. Finished sketches are hidden
/// once a feature uses them, like Fusion's default, unless shown one by one.
pub fn sketch_shown(s: &Session, id: u64) -> bool {
    sketch_drawn(s, id, true)
}

/// Is a sketch drawn, with the browser's Sketches folder shown (`folder`) or hidden? The sketch
/// being edited always is; otherwise not when hidden, nor in a hidden component, and one used by
/// a feature only when shown on its own.
pub fn sketch_drawn(s: &Session, id: u64, folder: bool) -> bool {
    let v = &s.visibility;
    if s.active_sketch == Some(id) {
        return true;
    }
    if v.hidden_sketches.contains(&id) || !sketch_component_visible(s, id) {
        return false;
    }
    v.shown_sketches.contains(&id) || (folder && !sketch_consumed(s, id))
}

/// Is the placement a sketch is drawn at shown (the active one while its component is being
/// edited, else the component's first)?
fn sketch_component_visible(s: &Session, id: u64) -> bool {
    if s.visibility.hidden_occurrences.is_empty() {
        return true;
    }
    let component = s.doc.feature(id).map_or(0, |f| f.component);
    if component == 0 {
        return true;
    }
    let path = match &s.active_occurrence_path {
        Some(p) if s.active_component == component => p.clone(),
        _ => s.doc.first_path(component),
    };
    s.occurrence_visible(&path)
}

/// Is a sketch used by a later feature?
pub fn sketch_consumed(s: &Session, id: u64) -> bool {
    use solidcraft_doc::FeatureKind;
    s.doc.features.iter().any(|f| matches!(f.kind, FeatureKind::Extrude { sketch, .. } | FeatureKind::Revolve { sketch, .. } if sketch == id))
}

/// Camera framing the model (iso view).
pub fn home_camera(s: &Session) -> Camera {
    let mut c = Camera::default();
    let b = bounds(s);
    if !b.is_empty() {
        c.fit(&b);
    } else {
        c.distance = 150.0;
    }
    c
}

/// Construction planes of the timeline, as evaluated: (feature id, name, plane).
pub fn construction_planes(s: &Session) -> Vec<(u64, String, Plane)> {
    constructs(s)
        .into_iter()
        .filter_map(|(id, name, g)| match g {
            solidcraft_doc::construct::ConstructGeom::Plane(p) => Some((id, name, p)),
            _ => None,
        })
        .collect()
}

/// Construction axes, as evaluated: (feature id, name, origin, unit direction).
pub fn construction_axes(s: &Session) -> Vec<(u64, String, Vec3, Vec3)> {
    constructs(s)
        .into_iter()
        .filter_map(|(id, name, g)| match g {
            solidcraft_doc::construct::ConstructGeom::Axis { origin, dir } => Some((id, name, origin, dir)),
            _ => None,
        })
        .collect()
}

/// Construction points, as evaluated: (feature id, name, position).
pub fn construction_points(s: &Session) -> Vec<(u64, String, Vec3)> {
    constructs(s)
        .into_iter()
        .filter_map(|(id, name, g)| match g {
            solidcraft_doc::construct::ConstructGeom::Point(p) => Some((id, name, p)),
            _ => None,
        })
        .collect()
}

/// Construction geometry of unsuppressed features, shown where its component is placed.
fn constructs(s: &Session) -> Vec<(u64, String, solidcraft_doc::construct::ConstructGeom)> {
    use solidcraft_doc::construct::ConstructGeom;
    let st = s.model.state();
    st.construct
        .iter()
        .filter_map(|c| {
            let f = s.doc.feature(c.feature).filter(|f| !f.suppressed)?;
            let m = s.doc.component_transform(f.component);
            if solidcraft_doc::is_identity(&m) {
                return Some((c.feature, c.name.clone(), c.geom.clone()));
            }
            let (pt, v) = (|p: Vec3| solidcraft_doc::apply_point(&m, p), |d: Vec3| solidcraft_doc::apply_vector(&m, d));
            let g = match &c.geom {
                ConstructGeom::Plane(p) => ConstructGeom::Plane(Plane::new(pt(p.origin), v(p.x), v(p.y)).unwrap_or(*p)),
                ConstructGeom::Axis { origin, dir } => ConstructGeom::Axis { origin: pt(*origin), dir: v(*dir) },
                ConstructGeom::Point(p) => ConstructGeom::Point(pt(*p)),
            };
            Some((c.feature, c.name.clone(), g))
        })
        .collect()
}

#[cfg(test)]
mod tests {
    use serde_json::json;

    use super::*;

    /// The CPU renderer (snapshots) shows appearances as the viewport does: a body's colour and
    /// faces with looks of their own.
    #[test]
    fn snapshot_scene_carries_appearances() {
        let mut s = Session::default();
        s.execute("solid.box", &json!({"length": 40, "width": 30, "height": 20})).unwrap();
        s.execute("solid.cylinder", &json!({"diameter": 14, "height": 30, "base": [50, 15, 0], "operation": "new"})).unwrap();
        s.execute("appearance.assign", &json!({"bodies": ["Body2"], "color": [220, 60, 40]})).unwrap();
        s.execute("appearance.assign", &json!({"faces": [[20, 15, 20]], "body": "Body1", "color": [40, 170, 80]})).unwrap();
        let cam = home_camera(&s);
        let sc = scene(&s, &cam);
        assert!(sc.meshes.iter().any(|m| m.color == Rgb(220, 60, 40)));
        assert!(sc.meshes.iter().any(|m| m.face_colors.iter().any(|(_, c)| *c == Rgb(40, 170, 80))));
        // And the rendered picture has the green top.
        let img = solidcraft_render::render(&sc, &cam, 200, 140);
        assert!(img.rgba.chunks(4).any(|p| p[1] > 120 && p[0] < 90 && p[2] < 110), "no green pixels");
    }

    /// Curved surfaces get a dark silhouette line in snapshots where they turn away.
    #[test]
    fn snapshots_draw_silhouettes_on_curved_surfaces() {
        let mut s = Session::default();
        s.execute("solid.sphere", &json!({"diameter": 20})).unwrap();
        let cam = home_camera(&s);
        let img = solidcraft_render::render(&scene(&s, &cam), &cam, 400, 400);
        let dark = img.rgba.chunks(4).filter(|p| p[0] < 70 && p[1] < 70 && p[2] < 75).count();
        assert!(dark > 40, "silhouette pixels: {dark}");
    }

    /// A section shows in snapshots: the cut part is gone and the cut face is drawn.
    #[test]
    fn snapshots_show_the_section() {
        let mut s = Session::default();
        s.execute("solid.box", &json!({"length": 40, "width": 30, "height": 20})).unwrap();
        let cam = home_camera(&s);
        let whole = solidcraft_render::render(&scene(&s, &cam), &cam, 200, 140).rgba;
        s.execute("inspect.section", &json!({"plane": {"origin": [0, 15, 0], "normal": [0, -1, 0]}})).unwrap();
        let sc = scene(&s, &cam);
        assert!(sc.clip.is_some());
        let cut = solidcraft_render::render(&sc, &cam, 200, 140).rgba;
        let changed = whole.chunks(4).zip(cut.chunks(4)).filter(|(a, b)| a != b).count();
        assert!(changed > 500, "{changed} pixels changed");
    }

    /// The section's cut face hides what lies inside the body behind it (it is drawn at the
    /// plane's depth, not on the far wall like a pane of glass), shows in the cap colour, and
    /// the cut's outline is drawn.
    #[test]
    fn snapshot_section_caps_hide_the_inside() {
        let mut s = Session::default();
        s.execute("solid.box", &json!({"length": 40, "width": 30, "height": 20})).unwrap();
        // Cut away the front half (y < 15), so the iso camera looks into the cut.
        s.execute("inspect.section", &json!({"plane": {"origin": [0, 15, 0], "normal": [0, -1, 0]}})).unwrap();
        for fov in [0.0, 0.6] {
            let mut cam = home_camera(&s);
            cam.fov = fov;
            let mut sc = scene(&s, &cam);
            assert!(!section_segments(&s.world_state().bodies[0].mesh(), Vec3::new(0.0, 15.0, 0.0), -Vec3::Y).is_empty());
            // A marker inside the body, behind the cut face.
            let red = Rgb(255, 0, 0);
            sc.lines.push(SceneLine { points: vec![Vec3::new(5.0, 25.0, 10.0), Vec3::new(35.0, 25.0, 10.0)], color: red, width: 3.0, on_top: false });
            let img = solidcraft_render::render(&sc, &cam, 300, 220);
            let px = || img.rgba.chunks(4);
            let marker = px().filter(|p| p[0] > 200 && p[1] < 60 && p[2] < 60).count();
            assert_eq!(marker, 0, "fov {fov}: the inside shows through the cut face");
            // The cap: warm (red over blue), unlike the grey-blue body and background.
            let cap = px().filter(|p| p[0] as i32 - p[2] as i32 > 20).count();
            assert!(cap > 500, "fov {fov}: cap pixels {cap}");
        }
    }
}

#[cfg(test)]
#[path = "view_display_tests.rs"]
mod display_tests;