Release more changes

Features
- Button to add samples to current render

Fixes
- Don't draw emitter arrows when rendering with rasterization
- (Previous commit) deal with non-uniform ray hit distance scaling
  systematically instead of deferring it to hit functions.

src/gui/widgets.cpp

@@ -761,7 +761,6 @@ bool Widget_Render::UI(Scene& scene, Widget_Camera& cam, Camera& user_cam, std::
 
         if(ImGui::Button("Cancel")) {
             pathtracer.cancel();
-            has_rendered = false;
         }
 
         ImGui::SameLine();
@@ -812,6 +811,13 @@ bool Widget_Render::UI(Scene& scene, Widget_Camera& cam, Camera& user_cam, std::
         }
     }
 
+    if(method == 1 && has_rendered) {
+        ImGui::SameLine();
+        if(ImGui::Button("Add Samples")) {
+            pathtracer.begin_render(scene, cam.get(), true);
+        }
+    }
+
     float avail = ImGui::GetContentRegionAvail().x;
     float w = std::min(avail, (float)out_w);
     float h = (w / out_w) * out_h;

src/rays/pathtracer.cpp

@@ -233,20 +233,22 @@ size_t Pathtracer::visualize_bvh(GL::Lines& lines, GL::Lines& active, size_t dep
     return scene.visualize(lines, active, depth, Mat4::I);
 }
 
-void Pathtracer::begin_render(Scene& layout_scene, const Camera& cam) {
+void Pathtracer::begin_render(Scene& layout_scene, const Camera& cam, bool add_samples) {
 
     size_t n_threads = std::thread::hardware_concurrency();
     size_t samples_per_epoch = std::max(size_t(1), n_samples / (n_threads * 10));
 
     cancel();
-
-    accumulator.clear({});
     total_epochs = n_samples / samples_per_epoch + !!(n_samples % samples_per_epoch);
 
+    if(!add_samples) {
+        accumulator.clear({});
+        accumulator_samples = 0;
         build_time = SDL_GetPerformanceCounter();
         build_scene(layout_scene);
+        build_time = SDL_GetPerformanceCounter() - build_time;
+    }
     render_time = SDL_GetPerformanceCounter();
-    build_time = render_time - build_time;
     
     camera = cam;
 
@@ -266,12 +268,11 @@ void Pathtracer::begin_render(Scene& layout_scene, const Camera& cam) {
 void Pathtracer::cancel() {
     cancel_flag = true;
     thread_pool.clear();
-    render_time = 0;
-    build_time = 0;
-    accumulator_samples = 0;
     completed_epochs = 0;
     total_epochs = 0;
     cancel_flag = false;
+    build_time = 0;
+    render_time = SDL_GetPerformanceCounter() - render_time;
 }
 
 const HDR_Image& Pathtracer::get_output() {

src/rays/pathtracer.h

@@ -32,7 +32,7 @@ public:
     const GL::Tex2D& get_output_texture(float exposure);
     size_t visualize_bvh(GL::Lines& lines, GL::Lines& active, size_t level);
 
-    void begin_render(Scene& scene, const Camera& camera);
+    void begin_render(Scene& scene, const Camera& camera, bool add_samples = false);
     void cancel();
     bool in_progress() const;
     float progress() const;

src/scene/particles.cpp

@@ -50,7 +50,7 @@ const GL::Mesh& Scene_Particles::mesh() const {
     return particle_instances.mesh();
 }
 
-void Scene_Particles::render(const Mat4& view, bool depth_only, bool posed) {
+void Scene_Particles::render(const Mat4& view, bool depth_only, bool posed, bool particles_only) {
 
     Renderer& renderer = Renderer::get();
 
@@ -62,7 +62,10 @@ void Scene_Particles::render(const Mat4& view, bool depth_only, bool posed) {
     opts.solid_color = true;
     opts.depth_only = depth_only;
     opts.color = opt.color.to_vec();
+
+    if(!particles_only) {
         renderer.mesh(arrow, opts);
+    }
 
     if(opt.enabled && !depth_only) {
         opts.modelview = view;

src/scene/particles.h

@@ -42,7 +42,7 @@ public:
     const std::vector<Particle>& get_particles() const;
 
     BBox bbox() const;
-    void render(const Mat4& view, bool depth_only = false, bool posed = true);
+    void render(const Mat4& view, bool depth_only = false, bool posed = true, bool particles_only = false);
     Scene_ID id() const;
     void set_time(float time);
 

src/scene/renderer.cpp

@@ -90,7 +90,12 @@ void Renderer::save(Scene& scene, const Camera& cam, int w, int h, int s) {
             Scene_Light& light = item.get<Scene_Light>();
             if(!light.is_env()) return;
         }
+
+        if(item.is<Scene_Particles>()) {
+            item.get<Scene_Particles>().render(view, false, true, true);
+        } else {
             item.render(view);
+        }
     });
 
     save_buffer.blit_to(0, save_output, true);