Laying some groundwork for a simple shading system.

src/parse/psy_assembly.rs

@@ -81,7 +81,7 @@ pub fn parse_assembly(tree: &DataTree) -> Result<Assembly, PsyParseError> {
                     }
                 }
 
-                // Sphere Light
+                // Rectangle Light
                 "RectangleLight" => {
                     if let &DataTree::Internal { ident: Some(ident), .. } = child {
                         builder.add_object(ident,
@@ -92,6 +92,17 @@ pub fn parse_assembly(tree: &DataTree) -> Result<Assembly, PsyParseError> {
                     }
                 }
 
+                // Surface shader
+                "SurfaceShader" => {
+                    if let &DataTree::Internal { ident: Some(ident), .. } = child {
+                        // TODO
+                        unimplemented!()
+                    } else {
+                        // TODO: error condition of some kind, because no ident
+                        panic!();
+                    }
+                }
+
                 _ => {
                     // TODO: some kind of error, because not a known type name
                 }
@@ -121,12 +132,6 @@ pub fn parse_assembly(tree: &DataTree) -> Result<Assembly, PsyParseError> {
                 //     assembly->add_surface_shader(child.name, parse_surface_shader(child));
                 // }
                 //
-                //
-                // // Rectangle Light
-                // else if (child.type == "RectangleLight") {
-                //     assembly->add_object(child.name, parse_rectangle_light(child));
-                // }
-                //
             }
         }
     } else {

src/renderer.rs

@@ -286,12 +286,8 @@ impl LightPath {
 
         // Result of shading ray, prepare light ray
         if self.round % 2 == 1 {
-            if let &surface::SurfaceIntersection::Hit { t: _,
+            if let &surface::SurfaceIntersection::Hit { intersection_data: idata, closure } =
-                                                        incoming: _,
+                isect {
-                                                        pos,
-                                                        nor,
-                                                        local_space: _,
-                                                        closure } = isect {
                 // Hit something!  Do the stuff
                 self.interaction = *isect; // Store interaction for use in next phase
 
@@ -310,7 +306,7 @@ impl LightPath {
                     // to the film plane if the light is not in shadow.
                     self.pending_color_addition = {
                         let material = closure.as_surface_closure();
-                        let la = material.evaluate(ray.dir, shadow_vec, nor, self.wavelength);
+                        let la = material.evaluate(ray.dir, shadow_vec, idata.nor, self.wavelength);
                         light_color * la * self.light_attenuation / (light_pdf * light_sel_pdf)
                     };
 
@@ -318,7 +314,7 @@ impl LightPath {
                     // in shadow or not.
                     // TODO: use proper ray offsets for avoiding self-shadowing
                     // rather than this hacky stupid stuff.
-                    *ray = Ray::new(pos + shadow_vec.normalized() * 0.001,
+                    *ray = Ray::new(idata.pos + shadow_vec.normalized() * 0.001,
                                     shadow_vec,
                                     self.time,
                                     true);
@@ -349,18 +345,14 @@ impl LightPath {
 
             // Calculate bounced lighting!
             if self.round < 6 {
-                if let surface::SurfaceIntersection::Hit { t: _,
+                if let surface::SurfaceIntersection::Hit { intersection_data: idata, closure } =
-                                                           pos,
+                    self.interaction {
-                                                           incoming,
-                                                           nor,
-                                                           local_space: _,
-                                                           closure } = self.interaction {
                     // Sample material
                     let (dir, filter, pdf) = {
                         let material = closure.as_surface_closure();
                         let u = self.next_lds_samp();
                         let v = self.next_lds_samp();
-                        material.sample(incoming, nor, (u, v), self.wavelength)
+                        material.sample(idata.incoming, idata.nor, (u, v), self.wavelength)
                     };
 
                     // Account for the additional light attenuation from
@@ -368,7 +360,7 @@ impl LightPath {
                     self.light_attenuation *= filter / pdf;
 
                     // Calculate the ray for this bounce
-                    *ray = Ray::new(pos + dir.normalized() * 0.0001, dir, self.time, false);
+                    *ray = Ray::new(idata.pos + dir.normalized() * 0.0001, dir, self.time, false);
 
                     return true;
                 } else {

src/scene/assembly.rs

@@ -42,7 +42,7 @@ impl Assembly {
                          time: f32,
                          intr: &SurfaceIntersection)
                          -> Option<(SpectralSample, Vector, f32, f32)> {
-        if let &SurfaceIntersection::Hit { pos, incoming, nor, closure, .. } = intr {
+        if let &SurfaceIntersection::Hit { intersection_data: idata, closure } = intr {
             let sel_xform = if xform_stack.top().len() > 0 {
                 lerp_slice(xform_stack.top(), time)
             } else {
@@ -50,9 +50,9 @@ impl Assembly {
             };
             if let Some((light_i, sel_pdf, whittled_n)) =
                 self.light_accel
-                    .select(incoming * sel_xform,
+                    .select(idata.incoming * sel_xform,
-                            pos * sel_xform,
+                            idata.pos * sel_xform,
-                            nor * sel_xform,
+                            idata.nor * sel_xform,
                             closure.as_surface_closure(),
                             time,
                             n) {
@@ -82,7 +82,7 @@ impl Assembly {
 
                                 // Sample the light
                                 let (color, shadow_vec, pdf) =
-                                    light.sample(&xform, pos, uvw.0, uvw.1, wavelength, time);
+                                    light.sample(&xform, idata.pos, uvw.0, uvw.1, wavelength, time);
                                 return Some((color, shadow_vec, pdf, sel_pdf));
                             }
 

src/shading/mod.rs

@@ -1 +1,41 @@
 pub mod surface_closure;
+
+use std::fmt::Debug;
+
+use self::surface_closure::SurfaceClosureUnion;
+use surface::SurfaceIntersectionData;
+
+/// Trait for surface shaders.
+pub trait SurfaceShader: Debug {
+    /// Takes the result of a surface intersection and returns the surface
+    /// closure to be evaluated at that intersection point.
+    fn shade(&self, data: &SurfaceIntersectionData) -> SurfaceClosureUnion;
+}
+
+/// Clearly we must eat this brownie before the world ends, lest it
+/// go uneaten before the world ends.  But to do so we must trek
+/// far--much like in Lord of the Rings--to fetch the golden fork with
+/// which to eat the brownie.  Only this fork can be used to eat this
+/// brownie, for any who try to eat it with a normal fork shall
+/// perish immediately and without honor.  But guarding the fork are
+/// three large donuts, which must all be eaten in sixty seconds or
+/// less to continue on.  It's called the donut challenge.  But these
+/// are no ordinary donuts.  To call them large is actually doing
+/// them a great injustice, for they are each the size of a small
+/// building.
+#[derive(Debug)]
+pub struct SimpleSurfaceShader {
+    closure: SurfaceClosureUnion,
+}
+
+impl SimpleSurfaceShader {
+    fn new(closure: SurfaceClosureUnion) -> SimpleSurfaceShader {
+        SimpleSurfaceShader { closure: closure }
+    }
+}
+
+impl SurfaceShader for SimpleSurfaceShader {
+    fn shade(&self, data: &SurfaceIntersectionData) -> SurfaceClosureUnion {
+        self.closure
+    }
+}

src/surface/mod.rs

@@ -11,20 +11,6 @@ use ray::{Ray, AccelRay};
 use shading::surface_closure::SurfaceClosureUnion;
 
 
-#[derive(Debug, Copy, Clone)]
-pub enum SurfaceIntersection {
-    Miss,
-    Occlude,
-    Hit {
-        t: f32,
-        pos: Point,
-        incoming: Vector,
-        nor: Normal,
-        local_space: Matrix4x4,
-        closure: SurfaceClosureUnion,
-    },
-}
-
 pub trait Surface: Boundable + Debug + Sync {
     fn intersect_rays(&self,
                       accel_rays: &mut [AccelRay],
@@ -32,3 +18,26 @@ pub trait Surface: Boundable + Debug + Sync {
                       isects: &mut [SurfaceIntersection],
                       space: &[Matrix4x4]);
 }
+
+
+#[derive(Debug, Copy, Clone)]
+pub enum SurfaceIntersection {
+    Miss,
+    Occlude,
+    Hit {
+        intersection_data: SurfaceIntersectionData,
+        closure: SurfaceClosureUnion,
+    },
+}
+
+
+#[derive(Debug, Copy, Clone)]
+pub struct SurfaceIntersectionData {
+    pub incoming: Vector, // Direction of the incoming ray
+    pub t: f32, // Ray t-value at the intersection point
+    pub pos: Point, // Position of the intersection
+    pub nor: Normal, // Shading normal
+    pub nor_g: Normal, // True geometric normal
+    pub uv: (f32, f32), // 2d surface parameters
+    pub local_space: Matrix4x4, // Matrix from global space to local space
+}

src/surface/triangle_mesh.rs

@@ -9,7 +9,7 @@ use math::{Point, Matrix4x4, cross};
 use ray::{Ray, AccelRay};
 use shading::surface_closure::{SurfaceClosureUnion, GTRClosure};
 
-use super::{Surface, SurfaceIntersection};
+use super::{Surface, SurfaceIntersection, SurfaceIntersectionData};
 use super::triangle;
 
 
@@ -92,11 +92,15 @@ impl Surface for TriangleMesh {
                             r.mark_done();
                         } else {
                             isects[r.id as usize] = SurfaceIntersection::Hit {
+                                intersection_data: SurfaceIntersectionData {
+                                    incoming: wr.dir,
                                     t: t,
                                     pos: wr.orig + (wr.dir * t),
-                                incoming: wr.dir,
+                                    nor: cross(tri.0 - tri.1, tri.0 - tri.2).into_normal(), // TODO
-                                nor: cross(tri.0 - tri.1, tri.0 - tri.2).into_normal(),
+                                    nor_g: cross(tri.0 - tri.1, tri.0 - tri.2).into_normal(),
+                                    uv: (0.0, 0.0), // TODO
                                     local_space: mat_space,
+                                },
                                 // TODO: get surface closure from surface shader.
                                 //closure: SurfaceClosureUnion::LambertClosure(
                                 //    LambertClosure::new(XYZ::new(0.8, 0.8, 0.8))