diff --git a/assets/voxygen/shaders/terrain-frag.glsl b/assets/voxygen/shaders/terrain-frag.glsl
index 95a5de0b05..034c98edcb 100644
--- a/assets/voxygen/shaders/terrain-frag.glsl
+++ b/assets/voxygen/shaders/terrain-frag.glsl
@@ -257,6 +257,37 @@ void main() {
     DirectionalLight sun_info = get_sun_info(sun_dir, point_shadow * sun_shade_frac, /*sun_pos*/f_pos);
     DirectionalLight moon_info = get_moon_info(moon_dir, point_shadow * moon_shade_frac/*, light_pos*/);
 
+    #ifdef EXPERIMENTAL_DIRECTIONALSHADOWMAPTEXELGRID
+        float offset_scale = 0.5;
+        vec3 offset_one = dFdx(f_pos) * offset_scale;
+        vec3 offset_two = dFdy(f_pos) * offset_scale;
+        vec3 one_up = f_pos + offset_one;
+        vec3 one_down = f_pos - offset_one;
+        vec3 two_up = f_pos + offset_two;
+        vec3 two_down = f_pos - offset_two;
+
+        // Adjust this to change the size of the grid cells relative to the
+        // number of shadow texels 
+        float grid_cell_to_texel_ratio = 32.0;
+
+        vec2 shadowTexSize = textureSize(sampler2D(t_directed_shadow_maps, s_directed_shadow_maps), 0) / grid_cell_to_texel_ratio;
+
+        vec4 one_up_shadow_tex = texture_mat * vec4(one_up, 1.0);
+        vec2 oust_snap = floor(one_up_shadow_tex.xy * shadowTexSize / one_up_shadow_tex.w);
+        vec4 one_down_shadow_tex = texture_mat * vec4(one_down, 1.0);
+        vec2 odst_snap = floor(one_down_shadow_tex.xy * shadowTexSize / one_down_shadow_tex.w);
+        vec4 two_up_shadow_tex = texture_mat * vec4(two_up, 1.0);
+        vec2 tust_snap = floor(two_up_shadow_tex.xy * shadowTexSize / two_up_shadow_tex.w);
+        vec4 two_down_shadow_tex = texture_mat * vec4(two_down, 1.0);
+        vec2 tdst_snap = floor(two_down_shadow_tex.xy * shadowTexSize / two_down_shadow_tex.w);
+        float border = length(max(abs(oust_snap - odst_snap), abs(tust_snap - tdst_snap)));
+
+        if (border != 0.0) {
+            tgt_color = vec4(vec3(0.0, 0.7, 0.2), 1.0);
+            return;
+        }
+    #endif
+     
     float max_light = 0.0;
 
     // After shadows are computed, we use a refracted sun and moon direction.
diff --git a/voxygen/src/render/mod.rs b/voxygen/src/render/mod.rs
index 4eee800bfc..9b50e4d4e8 100644
--- a/voxygen/src/render/mod.rs
+++ b/voxygen/src/render/mod.rs
@@ -462,6 +462,9 @@ pub enum ExperimentalShader {
     LowGlowNearCamera,
     /// Disable the fake voxel effect on LoD features.
     NoLodVoxels,
-    // Disable the 'pop-in' effect when loading terrain.
+    /// Disable the 'pop-in' effect when loading terrain.
     NoTerrainPop,
+    /// Display grid lines to visualize the distribution of shadow map texels
+    /// for the directional light from the sun.
+    DirectionalShadowMapTexelGrid,
 }
diff --git a/voxygen/src/render/pipelines/mod.rs b/voxygen/src/render/pipelines/mod.rs
index fe5f1f684d..0fad8f5598 100644
--- a/voxygen/src/render/pipelines/mod.rs
+++ b/voxygen/src/render/pipelines/mod.rs
@@ -50,7 +50,9 @@ pub struct Globals {
     /// aligned.
     view_distance: [f32; 4],
     time_of_day: [f32; 4], // TODO: Make this f64.
+    /// Direction of sunlight.
     sun_dir: [f32; 4],
+    /// Direction of moonlight.
     moon_dir: [f32; 4],
     tick: [f32; 4],
     /// x, y represent the resolution of the screen;
@@ -163,11 +165,13 @@ impl Globals {
         time_of_day as f32 * TIME_FACTOR
     }
 
+    /// Computes the direction of light from the sun based on the time of day.
     pub fn get_sun_dir(time_of_day: f64) -> Vec3<f32> {
         let angle_rad = Self::get_angle_rad(time_of_day);
         Vec3::new(-angle_rad.sin(), 0.0, angle_rad.cos())
     }
 
+    /// Computes the direction of light from the moon based on the time of day.
     pub fn get_moon_dir(time_of_day: f64) -> Vec3<f32> {
         let angle_rad = Self::get_angle_rad(time_of_day);
         -Vec3::new(-angle_rad.sin(), 0.0, angle_rad.cos() - 0.5).normalized()
diff --git a/voxygen/src/scene/math.rs b/voxygen/src/scene/math.rs
index dcf55404e7..41c2ae6749 100644
--- a/voxygen/src/scene/math.rs
+++ b/voxygen/src/scene/math.rs
@@ -366,6 +366,14 @@ pub fn calc_focused_light_volume_points<T: Float + MulAdd<T, T, Output = T> + co
     ) */
 }
 
+/// Computes an axis aligned bounding box that contains the provided points when
+/// transformed into the coordinate space specificed by `mat`.
+///
+/// "psr" stands for "Potential shadow receivers" since this function is used to
+/// get an Aabb containing the potential points (which represent the extents of
+/// the volumes of potential things that will be shadowed) that will be
+/// shadowed.
+///
 /// NOTE: Will not yield useful results if pts is empty!
 pub fn fit_psr<
     T: Float + MulAdd<T, T, Output = T>,