From c8d47800eb4d85a26216da3ff938d530be32dbf0 Mon Sep 17 00:00:00 2001
From: Anton Lydike <me@antonlydike.de>
Date: Fri, 24 Apr 2020 16:51:22 +0200
Subject: [PATCH] performance improvements

---
 README.md   |  8 ++++++++
 main.c      |  8 ++++----
 marcher.h   | 13 ++++++++++---
 src/scene.c | 21 ++++++++++++++++-----
 4 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index 49f3274..fef9d19 100644
--- a/README.md
+++ b/README.md
@@ -9,4 +9,12 @@ in fish:
 nix-shell --run fish
 # run gcc with flags
 gcc (pkg-config --cflags --libs gtk+-3.0 | string split " ") -lm -Wall -Wextra -o march.out main.c
+```
+
+## Running
+
+give it the number of threads you want to use
+
+```bash
+./march.out <num threads>
 ```
\ No newline at end of file
diff --git a/main.c b/main.c
index 3bc132e..632880b 100644
--- a/main.c
+++ b/main.c
@@ -122,9 +122,10 @@ int main(int argc, char* argv[]) {
     printf("threads: %d\n", threads);
 
     // create basic scene with up to 10 objects
-    Scene scene = scene_new(4000, 4000, 10);
-    scene.max_steps = 1000;
-    scene.threshold = 0.0001;
+    Scene scene = scene_new(1000, 1000, 10);
+    scene.perf_opts.max_steps = 1000;
+    scene.perf_opts.threshold = 0.0001;
+    scene.perf_opts.speed_cutoff = 10;
     scene.background = color_new(255,255,255);
 
     //scene_add_obj(&scene, circle_new(pt_new(SCENE_MOD / 2.0, SCENE_MOD/ 2.0, SCENE_MOD / 2.0), .2));
@@ -140,4 +141,3 @@ int main(int argc, char* argv[]) {
 
     return 0;  
 }
-
diff --git a/marcher.h b/marcher.h
index 69d906f..acc539a 100644
--- a/marcher.h
+++ b/marcher.h
@@ -62,15 +62,22 @@ typedef struct __myobject {
     struct __myscene* scene;
 } SceneObject;
 
+
+typedef struct __perfopts {
+    int speed_cutoff;
+    int max_steps;
+    double threshold;
+} PerformanceOptimizations;
+
+
 typedef struct __myscene {
     unsigned int width;
     unsigned int height;
     SceneObject * objects;
     int object_count;
     int allocated_space;
-    // some other settings
-    int max_steps;
-    double threshold;
+    // performance opts
+    PerformanceOptimizations perf_opts;
     // colors etc
     Color background;
 } Scene;
diff --git a/src/scene.c b/src/scene.c
index 65e9190..34f9a90 100644
--- a/src/scene.c
+++ b/src/scene.c
@@ -15,12 +15,18 @@ Scene scene_new(unsigned int width, unsigned int height, int obj_count) {
     Scene scene;
     scene.height = height;
     scene.width = width;
-    scene.max_steps = 32;
-    scene.threshold = 0.02;
     scene.object_count = 0;
     scene.objects = malloc(obj_count * sizeof(SceneObject));
     scene.allocated_space = obj_count;
     scene.background = color_new(0,0,0);
+
+    PerformanceOptimizations perf_opts;
+    perf_opts.speed_cutoff = 0;
+    perf_opts.max_steps = 32;
+    perf_opts.threshold = 0.02;
+
+    scene.perf_opts = perf_opts;
+
     return scene;
 }
 
@@ -71,8 +77,9 @@ Color march_ray(Point origin, Point direction, Scene* scene) {
     SceneObject* closest_obj = scene->objects;
 
     // get steps, threshold from scene
-    int steps = scene->max_steps;
-    double threshold = scene->threshold;
+    int steps = scene->perf_opts.max_steps;
+    double threshold = scene->perf_opts.threshold;
+    int speed_cutoff = scene->perf_opts.speed_cutoff;
 
     // as long as we did not max out steps, or got very close to an object
     while (steps > 0 && dist > threshold) {
@@ -91,6 +98,10 @@ Color march_ray(Point origin, Point direction, Scene* scene) {
             }
         }
 
+        if (speed_cutoff > 0 && speed_cutoff < dist) {
+            break;
+        }
+
         // write down our closest encounter
         if (dist < closest_encounter) closest_encounter = dist;
 
@@ -107,7 +118,7 @@ Color march_ray(Point origin, Point direction, Scene* scene) {
         // a hit!
         #ifndef SCENE_NO_AM_OCC
         
-        double f = (steps / (double) scene->max_steps);
+        double f = (steps / (double) scene->perf_opts.max_steps);
         f = f * f * f * f; // to the fourth power to make smaller values bigger
 
         Color c = closest_obj->get_color(pos, direction, closest_obj);