From 430761da2e25776602ee5961326f5bd7775b57c8 Mon Sep 17 00:00:00 2001
From: Hunter Kvalevog <hunter@kvog.sh>
Date: Sun, 31 May 2026 21:29:28 -0500
Subject:

---
 vk-cube/vk-cube-fs.glsl | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

(limited to 'vk-cube/vk-cube-fs.glsl')

diff --git a/vk-cube/vk-cube-fs.glsl b/vk-cube/vk-cube-fs.glsl
index 1262747..622d2bd 100644
--- a/vk-cube/vk-cube-fs.glsl
+++ b/vk-cube/vk-cube-fs.glsl
@@ -1,12 +1,12 @@
 #version 450
 // ================================================================================================
-// Fragment shader
+// Fragment shader, basic Phong shading
 //
 // Build:
 //     $ glslc -o vk-cube-fs.spv -fshader-stage=fragment vk-cube-fs.glsl
 //
 // Changelog:
-//     ??/??/????: Initial release
+//     5/31/2026: Initial release
 //
 // License:
 //     Copyright (c) 2026 Hunter Kvalevog
@@ -18,10 +18,30 @@
 //     WITH REGARD TO THIS SOFTWARE.
 // ================================================================================================
 
+layout (location = 0) in vec3 f_c;
+layout (location = 1) in vec3 f_n;
+layout (location = 2) in vec3 f_p;
+
 layout (location = 0) out vec4 out_color;
 
 void main()
 {
-    out_color = vec4(1.0f, 0.0f, 0.0f, 1.0f);
+    vec3 light_pos = vec3(0.0f, 0.0f, -2.0f);
+    vec3 light_dir = normalize(light_pos - f_p);
+    vec3 view_dir  = normalize(-f_p);
+
+    // ambient
+    float ambient = 0.15f;
+
+    // diffuse
+    float diffuse = max(dot(f_n, light_dir), 0.0f);
+
+    // specular
+    vec3 reflect_dir = reflect(-light_dir, f_n);
+    float spec = pow(max(dot(view_dir, reflect_dir), 0.0f), 32.0f);
+
+    vec3 result = (ambient + diffuse + 0.5 * spec) * f_c;
+
+    out_color = vec4(result, 1.0f);
 }
 
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