+ | First sphere

shaders/frag.frag

@@ -0,0 +1,75 @@
+#version 430 core
+out vec4        FragColor;
+
+uniform vec2    u_resolution;
+
+vec3 sphereCenter = vec3(0.0, 0.0, -5.0);
+float sphereRadius = 1.0;
+
+
+vec3 lightPos = vec3(5.0, 5.0, 5.0);
+vec3 lightColor = vec3(1.0, 1.0, 1.0);
+vec3 objectColor = vec3(0.4, 0.7, 0.9); 
+
+
+struct Ray {
+    vec3 origin;
+    vec3 direction;
+};
+
+
+bool intersectSphere(Ray ray, vec3 center, float radius, out float t) {
+    vec3 oc = ray.origin - center;
+    float a = dot(ray.direction, ray.direction);
+    float b = 2.0 * dot(oc, ray.direction);
+    float c = dot(oc, oc) - radius * radius;
+    float discriminant = b * b - 4.0 * a * c;
+    
+    if (discriminant < 0.0) {
+        return false;
+    } else {
+        t = (-b - sqrt(discriminant)) / (2.0 * a);
+        return true;
+    }
+}
+
+
+vec3 computeLighting(vec3 point, vec3 normal, vec3 viewDir) {
+    vec3 lightDir = normalize(lightPos - point);
+    float diff = max(dot(normal, lightDir), 0.0);
+    
+    
+    vec3 diffuse = diff * lightColor;
+
+    
+    return objectColor * diffuse;
+}
+
+
+void    main()
+{
+	vec2    uv;
+	vec4    color;
+
+	uv = gl_FragCoord.xy / u_resolution.xy * 2.0 - 1.0;
+	uv.x *= u_resolution.x / u_resolution.y;
+
+	vec3 rayOrigin = vec3(0.0, 0.0, 0.0); 
+    vec3 rayDirection = normalize(vec3(uv, -1.0)); 
+
+    Ray ray = Ray(rayOrigin, rayDirection);
+    
+    float t;
+    if (intersectSphere(ray, sphereCenter, sphereRadius, t))
+	{
+        vec3 hitPoint = ray.origin + t * ray.direction;
+        vec3 normal = normalize(hitPoint - sphereCenter);
+
+        vec3 viewDir = normalize(-ray.direction);
+
+        vec3 color = computeLighting(hitPoint, normal, viewDir);
+        FragColor = vec4(color, 1.0);
+    } else {
+        FragColor = vec4(0.0, 0.0, 0.0, 1.0); 
+    }
+}