From 8ccc424b0634478544fcf668f816f68cc42c5cf3 Mon Sep 17 00:00:00 2001
From: Abdelrahman <said.abdelrahman89@gmail.com>
Date: Sat, 24 Aug 2024 23:16:11 +0100
Subject: [PATCH] Calculate light direction from position

---
 src/shader/shaders.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/shader/shaders.c b/src/shader/shaders.c
index 1d1d9d2..2a2bfb9 100644
--- a/src/shader/shaders.c
+++ b/src/shader/shaders.c
@@ -130,9 +130,11 @@ internal FragmentResult phong_shader_fragment(void *shader,
   // Ambient term
   V3f intensity = num_mul_v3(g_ambient_light, model->material.ambient);
 
-  V4f hdir = V3_to_V4(g_directional_light.direction);
+  V4f hdir = V3_to_V4(g_directional_light.position);
   hdir = mat4x4_mul_vec4(matrix, hdir);
-  V3f light_dir = project_vec4(hdir);
+  V3f light_pos = project_vec4(hdir);
+  normalise_v3(light_pos);
+  V3f light_dir = sub_v3(light_pos, data->position);
 
   // Diffuse term
   f32 l_dot_n = dot_v3(norm, light_dir);
@@ -147,7 +149,9 @@ internal FragmentResult phong_shader_fragment(void *shader,
   // Specular term
   V3f _2_l_dot_n_norm = num_mul_v3(norm, 2.0f * l_dot_n);
   V3f reflected = sub_v3(_2_l_dot_n_norm, light_dir);
+  normalise_v3(reflected);
   V3f v = sub_v3(g_eye, data->position);
+  normalise_v3(v);
   f32 r_dot_v = dot_v3(reflected, v);
   if (r_dot_v <= 0.0f) {
     goto RETURN_OUTPUT_COLOUR;
@@ -193,7 +197,7 @@ internal M4x4f get_projection_matrix(ProjectionType projection_type) {
 }
 
 internal f32 get_intensity(const V3f *normal) {
-  V3f light = g_directional_light.direction;
+  V3f light = g_directional_light.position;
   normalise_v3(light);
 
   f32 intensity = dot_v3((*normal), light);