Different approach, not truly ambient light (kind of "see-through sph…

…ere"), avoids aliasing near the horizon.

CMakeLists.txt

@@ -448,7 +448,7 @@ function(trace ray_origin ray_dir depth color)
 
         trace(new_origin new_dir ${depth} traced_col)
 
-        set(col ${light_color_ambient})
+        set(col 0 0 0)
         light_contrib(hit_point_1 hit_normal_1 light1_pos light1_col out_col1)
         light_contrib(hit_point_1 hit_normal_1 light2_pos light2_col out_col2)
         vec3_add(col out_col1 col)
@@ -459,7 +459,7 @@ function(trace ray_origin ray_dir depth color)
         vec3_mul(base_col col col)
 
     elseif(${hit_t_2} GREATER ${ray_epsilon})
-        set(light_col ${light_color_ambient})
+        set(light_col 0 0 0)
 
         list(GET hit_point_2 0 hit_p_x)
         list(GET hit_point_2 2 hit_p_z)
@@ -470,11 +470,12 @@ function(trace ray_origin ray_dir depth color)
         mul(${shadow_offset_z} ${shadow_offset_z} shadow_offset_z_2)
         add(${shadow_offset_x_2} ${shadow_offset_z_2} hit_dist_2)
 
-        if(${hit_dist_2} GREATER_EQUAL ${shadow_radius2})
-            light_contrib(hit_point_2 hit_normal_2 light1_pos light1_col out_col1)
-            light_contrib(hit_point_2 hit_normal_2 light2_pos light2_col out_col2)
-            vec3_add(light_col out_col1 light_col)
-            vec3_add(light_col out_col2 light_col)
+        light_contrib(hit_point_2 hit_normal_2 light1_pos light1_col out_col1)
+        light_contrib(hit_point_2 hit_normal_2 light2_pos light2_col out_col2)
+        vec3_add(light_col out_col1 light_col)
+        vec3_add(light_col out_col2 light_col)
+        if(${hit_dist_2} LESS ${shadow_radius2})
+          vec3_mulf(light_col ${tenth} light_col)
         endif()
 
         # Calculate checkerboard pattern
@@ -509,14 +510,14 @@ endfunction()
 
 to_fp(255.99 rgb_scaling)
 to_fp(0.5 half)
+to_fp(0.1 tenth)
 to_fp(${image_width} image_width_fp)
 to_fp(${image_height} image_height_fp)
 to_fp(0.01 ray_epsilon)
 
 to_fp(2 sphere_radius)
 vec3_to_fp(0.0 0.0 3.0 sphere_center)
 vec3_to_fp(0.3 0.3 0.3 sphere_color)
-vec3_to_fp(0.05 0.05 0.05 light_color_ambient)
 
 to_fp(3.0 shadow_center)
 to_fp(4 shadow_radius2)