Refactor: move hitlist, object, sphere, viewport into single files.

Add bias_ctx for setting sub-pixel sampling bias.

1 files changed, 6 insertions, 167 deletions

diff --git a/main_simple_scanner.cpp b/main_simple_scanner.cpp
index 7769c0f..6dadf30 100644
--- a/main_simple_scanner.cpp
+++ b/main_simple_scanner.cpp
@@ -5,192 +5,31 @@
 #include <cstdint>
 #include <iostream>
 #include <vector>
-#include <limits>
 #include <memory>
 #include <cstdlib>
 
 #include "vec.h"
-#include "ray.h"
-#include "bitmap.h"
 #include "timer.h"
+#include "viewport.h"
+#include "hitlist.h"
+#include "sphere.h"
 
 #define DEMO_BALL
 
-class object {
-public:
-    // Will the given ray hit. Returns time t if hits in range [t1, t2].
-    virtual bool hit(const ray3d &r, double &t, double t1, double t2) const = 0;
-
-    // With t2 = infinity
-    inline bool hit(const ray3d &r, double &t, double t1) const {
-        return hit(r, t, t1, std::numeric_limits<double>::infinity());
-    }
-
-    // Given a point on the surface, returns the normalized outer normal vector on that point.
-    virtual vec3d normal_vector(const vec3d &where) const = 0;
-
-    // object color, currently not parameterized
-    virtual pixel8b color() const = 0;
-
-    // subclasses must have virtual destructors
-    virtual ~object() = default;
-};
-
-class sphere : public object {
-    vec3d center;
-    double radius;
-
-public:
-    sphere() = delete;
-
-    sphere(const vec3d &center, double radius) : center(center), radius(radius) {}
-
-    ~sphere() override = default;
-
-    vec3d normal_vector(const vec3d &where) const override {
-        // We assume the point is on surface, speeding up the normalization
-        return (where - center) / radius;
-    }
-
-    bool hit(const ray3d &r, double &t, double t1, double t2) const override {
-        // Ray: {Source, Direction, time}
-        // Sphere: {Center, radius}
-        // sphere hit formula: |Source + Direction * time - Center| = radius
-        // |(Sx + Dx * t - Cx, Sy + Dy * t - Cy, Sz + Dz * t - Cz)| = radius
-
-        const auto c2s = r.source() - center; // center to source
-        // A = D dot D
-        const double a = r.direction().mod2();
-        // H = (S - C) dot D
-        const auto h = dot(c2s, r.direction());
-        // B = 2H ( not used in our optimized routine )
-        // C = (S - C) dot (S - C) - radius^2
-        const double c = c2s.mod2() - radius * radius;
-        // 4delta = H^2 - AC
-        // delta_q = H^2 - AC (quarter delta)
-        const double delta_q = h * h - a * c;
-
-        bool hit = false;
-        if (delta_q >= 0) {
-            // return the root in range [t1, t2]
-            // t = ( -H +- sqrt{ delta_q } ) / A
-            double root;
-            root = (-h - sqrt(delta_q)) / a;
-            if (root >= t1 && root <= t2) {
-                hit = true;
-                t = root;
-            } else {
-                root = (-h + sqrt(delta_q)) / a;
-                if (root >= t1 && root <= t2) {
-                    hit = true;
-                    t = root;
-                }
-            }
-        }
-        return hit;
-    }
-
-    pixel8b color() const override {
-        return pixel8b::from_normalized(1.0, 0.0, 0.0);
-    }
-};
-
-// A world
-class hitlist {
-    std::vector<std::shared_ptr<object>> objects;
-
-public:
-    hitlist() = default;
-
-    hitlist(hitlist &other) = delete; // do not copy the world
-
-    // Add an object to the world.
-    void add_object(std::shared_ptr<object> &&obj) {
-        objects.push_back(std::move(obj));
-    }
-
-    // Given a ray, compute the color.
-    pixel8b color(const ray3d &r) const {
-        // Detect hits
-        bool hit = false;
-        double hit_t = std::numeric_limits<double>::infinity();
-        std::shared_ptr<object> hit_obj;
-        // Check the nearest object we hit
-        for (const auto &obj: objects) {
-            double t_;
-            if (obj->hit(r, t_, 0.0) && t_ < hit_t) {
-                hit = true;
-                hit_t = t_;
-                hit_obj = obj;
-            }
-        }
-        if (hit) {
-            // normal vector on hit point
-            const auto nv = hit_obj->normal_vector(r.at(hit_t));
-//                return obj->color();
-            // visualize normal vector at hit point
-            return pixel8b::from_normalized(nv);
-        }
-
-
-        // Does not hit anything. Get background color (infinity)
-        const auto u = (r.direction().y + 1.0) * 0.5;
-        return mix(
-                pixel8b::from_normalized(1.0, 1.0, 1.0),
-                pixel8b::from_normalized(0.5, 0.7, 1.0),
-                1.0 - u,
-                u
-        );
-    }
-
-
-};
-
-class viewport {
-    double half_width, half_height; // viewport size
-    vec3d center; // coordinate of the viewport center point
-
-public:
-    viewport() = delete;
-
-    viewport(double width, double height, vec3d viewport_center) :
-            half_width(width / 2.0), half_height(height / 2.0), center(viewport_center) {}
-
-    // Generate the image seen on given viewpoint.
-    bitmap8b render(const hitlist &world, vec3d viewpoint, uint16_t image_width, uint16_t image_height) const {
-        bitmap8b image{image_width, image_height};
-        const auto r = center - viewpoint;
-        const int img_hw = image_width / 2, img_hh = image_height / 2;
-        // iterate over every pixel on the image
-        for (int j = -img_hh + 1; j <= img_hh; ++j) { // axis y, transformation is needed
-            for (int i = -img_hw; i < img_hw; ++i) { // axis x
-                const vec3d off{
-                        .x=1.0 * i / img_hw * half_width,
-                        .y=1.0 * j / img_hh * half_height,
-                        .z=0.0
-                }; // offset on screen plane
-                const auto dir = r + off; // direction vector from camera to current pixel on screen
-                const ray3d ray{viewpoint, dir}; // from camera to pixel (on the viewport)
-                const auto pixel = world.color(ray);
-                image.set(i + img_hw, -j + img_hh, pixel);
-            }
-        }
-        return image;
-    }
-};
-
 void generate_image(uint16_t image_width, uint16_t image_height, double viewport_width, double focal_length,
                     double sphere_z, double sphere_r, const std::string &caption = "", unsigned caption_scale = 1) {
     double r = 1.0 * image_width / image_height;
     viewport vp{viewport_width, viewport_width / r, vec3d{0, 0, -focal_length}};
     hitlist world;
+    bias_ctx bias{false, 0};
     world.add_object(std::make_shared<sphere>(
             vec3d{0, -100.5, -1},
             100)); // the earth
     world.add_object(std::make_shared<sphere>(vec3d{0, 0, sphere_z}, sphere_r));
     timer tm;
     tm.start_measure();
-    auto image = vp.render(world, vec3d::zero(), image_width, image_height); // camera position as the coordinate origin
+    auto image = vp.render(world, vec3d::zero(),
+                           image_width, image_height, bias); // camera position as the coordinate origin
     tm.stop_measure();
     if (!caption.empty()) {
         image.print(caption,