From 1de2dae2230d81bd44204771a436146c91dc7198 Mon Sep 17 00:00:00 2001
From: Amy Retzerau <amy.retzerau@gmail.com>
Date: Wed, 27 Aug 2025 16:00:02 +0200
Subject: [PATCH] feat: added normal calc

---
 sdf.fs | 90 ++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 60 insertions(+), 30 deletions(-)

diff --git a/sdf.fs b/sdf.fs
index 402d79b..f79e90a 100644
--- a/sdf.fs
+++ b/sdf.fs
@@ -4,10 +4,10 @@ R"###(
 out vec4 FragColor;
 in vec2 texCoords;
 
-vec3 center = vec3(0.0f,0.0f,20.0f);
-float radius = 5.0f;
+vec3 center = vec3(0.0,0.0,20.0);
+float radius = 5.0;
 
-float planeHeight = -7.0f;
+float planeHeight = -7.0;
 
 struct Ray {
     vec3 dir;
@@ -25,52 +25,82 @@ Ray applyMin(Ray ray) {
 }
 
 
-Ray planeMin(Ray ray){
-    ray.min = ray.pos.y - planeHeight;
-    ray.color = vec3(1.0,1.0,1.0);
-    return applyMin(ray);
+float planeMin(vec3 pos){
+    return pos.y - planeHeight;
 }
 
-Ray sphereMin(Ray ray){
-    ray.min = length(ray.pos - center) - radius;
-    ray.color = vec3(1.0,0.0,0.0);
-    return applyMin(ray);
+float sphereMin(vec3 pos){
+    return length(pos - center) - radius;
 }
 
 Ray minFn(Ray ray){
-    Ray sp = sphereMin(ray);
-    Ray pl = planeMin(ray);
+    float sp = sphereMin(ray.pos);
+    float pl = planeMin(ray.pos);
 
-    if (sp.min < pl.min){
+
+    
+
+    if (sp < pl){
+        ray.color = vec3(1.0, 0.5, 0.2);
+        ray.min = sp;
+    } else {
+        ray.color = vec3(1.,1.,1.);
+        ray.min = pl;
+    }
+    return applyMin(ray);
+    }
+
+float minFn(vec3 pos){
+    float sp = sphereMin(pos);
+    float pl = planeMin(pos);
+
+    if (sp < pl){
         return sp;
     } else {
         return pl;
     }
 }
 
+Ray march(Ray ray){
+    //ray.min = minFn(ray.pos);
+    ray = minFn(ray);
+    int c = 0;
+    while(( c < 200) && (ray.min < 100.0f) && (ray.min > 0.1f) ) {
+        ray = minFn(ray);    
+        c++;
+    }
+
+    return ray;
+}
+
+vec3 calcNormal(Ray ray){
+
+    float h = 0.001;
+    float m = sphereMin(ray.pos);
+    vec3 n = vec3(
+        minFn(ray.pos + vec3( h,.0,.0)) - minFn(ray.pos - vec3( h,.0,.0)),
+        minFn(ray.pos + vec3(.0, h,.0)) - minFn(ray.pos - vec3(.0, h,.0)),
+        minFn(ray.pos + vec3(.0,.0, h)) - minFn(ray.pos - vec3(.0,.0, h))
+    );
+
+    return normalize(n);
+}
+
 void main()
 {
-    vec3 dir = vec3(texCoords.x, texCoords.y,2.0f);
-    dir = (dir - 0.5f) * 2;
+    vec3 dir = vec3((texCoords - 0.5)*2,1.0);
     vec3 pos = dir;
     Ray ray = Ray(pos,normalize(dir),.0,.0,vec3(.0));
 
+    ray = march(ray);        
+    vec3 normal = calcNormal(ray);
+    vec3 lighDir = normalize(vec3(.5,-1.0,0.5));
+    float light = (.5 - min(dot(normal,lighDir),0.0))*2.;
 
-    ray = minFn(ray);
-
-    while( (ray.min < 100.0f) && (ray.min > 0.1f) ) {
-        //ray.dir = normalize(ray.dir);
-        ray = minFn(ray);
-        //vec3 off = ray.dir * min;
-        //ray.pos = ray.pos + off;
-        
-    }
-    
-    
-    if(ray.min <= 0.2f){
-        FragColor = vec4(ray.color, 1.0f);
+    if(ray.min <= 0.2){
+        FragColor = vec4(ray.color * light, 1.0);
     } else {
-        FragColor = vec4(.0,0.0f,0.0f,1.0f);
+        FragColor = vec4(.0,0.0,0.0,1.0);
     }
 
 }