Update teapot model, add phong shading, & more

1 files changed, 16 insertions, 3 deletions

diff --git a/shaders/obj.frag.slang b/shaders/obj.frag.slang
index 90525a3..6f6661c 100644
--- a/shaders/obj.frag.slang
+++ b/shaders/obj.frag.slang
@@ -18,17 +18,30 @@
  */
 
 struct FSInput {
-    float3 normal : TEXCOORD0;
+    float3 normal          : TEXCOORD0;
+    float3 world_position  : TEXCOORD1;
+    float3 camera_position : TEXCOORD2;
 };
 
 struct FSOutput {
     float4 out_color : SV_Target0;
 };
 
+static const float ambient_strength  = 0.22;
+static const float diffuse_strength  = 0.78;
+static const float specular_strength = 0.6;
+static const float shininess         = 32.0;
+
 FSOutput main(FSInput input) {
     float3 light_direction = normalize(float3(-0.45, 0.75, 0.55));
-    float light = max(dot(normalize(input.normal), light_direction), 0.0);
-    float shade = 0.22 + light * 0.78;
+    float3 normal = normalize(input.normal);
+    float3 view_direction = normalize(input.camera_position - input.world_position);
+    float3 reflect_direction = reflect(-light_direction, normal);
+
+    float diffuse = max(dot(normal, light_direction), 0.0);
+    float specular = diffuse > 0.0 ? pow(max(dot(view_direction, reflect_direction), 0.0), shininess) : 0.0;
+
+    float shade = saturate(ambient_strength + diffuse * diffuse_strength + specular * specular_strength);
     FSOutput output;
     output.out_color = float4(shade, shade, shade, 1.0);
     return output;