From 088d2077a1bc523d63d817cc1e4488023d7b43b3 Mon Sep 17 00:00:00 2001
From: Imbris <imbrisf@gmail.com>
Date: Sat, 24 Jul 2021 01:10:29 -0400
Subject: [PATCH] Add ability to edit shader to enable filtering dim values for
 experimentation

---
 .../dual-downsample-filtered-frag.glsl        | 31 ++++++++++++++-----
 voxygen/src/render/renderer/drawer.rs         | 15 +++++++--
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/assets/voxygen/shaders/dual-downsample-filtered-frag.glsl b/assets/voxygen/shaders/dual-downsample-filtered-frag.glsl
index 01235bf798..b4a54ec5c6 100644
--- a/assets/voxygen/shaders/dual-downsample-filtered-frag.glsl
+++ b/assets/voxygen/shaders/dual-downsample-filtered-frag.glsl
@@ -14,27 +14,27 @@ layout(location = 0) in vec2 uv;
 
 layout(location = 0) out vec4 tgt_color;
 
-vec4 simplesample(vec2 uv) {
-    return textureLod(sampler2D(t_src_color, s_src_color), uv, 0);
+vec4 simplefetch(ivec2 uv) {
+    return texelFetch(sampler2D(t_src_color, s_src_color), uv, 0);
 }
 
 // check whether the texel color is higher than threshold, if so output as brightness color
 vec4 filterDim(vec4 color) {
     // TODO: note where this constant came from if we keep it
     float brightness = dot(color.rgb, vec3(0.2126, 0.7152, 0.0722));
-    if(brightness > 1.0)
+    if(brightness > 1.00)
         return vec4(color.rgb, 1.0);
     else
         return vec4(0.0, 0.0, 0.0, 1.0);
 }
 
 vec4 filteredFetch(ivec2 uv) {
-    return filterDim(simplesample(uv));
+    return filterDim(simplefetch(uv));
 }
 
 // Derived from: https://community.arm.com/cfs-file/__key/communityserver-blogs-components-weblogfiles/00-00-00-20-66/siggraph2015_2D00_mmg_2D00_marius_2D00_notes.pdf
 vec4 filteredDownsample(vec2 uv, vec2 halfpixel) {
-    vec2 tex_res = 2.0 / halfpixel;
+    vec2 tex_res = 0.5 / halfpixel;
     // coordinate of the top left texel
     //  _ _ _ _
     // |x|_|_|_|
@@ -68,6 +68,23 @@ vec4 filteredDownsample(vec2 uv, vec2 halfpixel) {
     return sum / 32.0;
 }
 
-void main() {
-    tgt_color = filteredDownsample(uv, halfpixel);
+vec4 simplesample(vec2 uv) {
+    return textureLod(sampler2D(t_src_color, s_src_color), uv, 0);
+}
+
+// From: https://community.arm.com/cfs-file/__key/communityserver-blogs-components-weblogfiles/00-00-00-20-66/siggraph2015_2D00_mmg_2D00_marius_2D00_notes.pdf
+vec4 downsample(vec2 uv, vec2 halfpixel) {
+    vec4 sum = simplesample(uv) * 4.0;
+    sum += simplesample(uv - halfpixel.xy);
+    sum += simplesample(uv + halfpixel.xy);
+    sum += simplesample(uv + vec2(halfpixel.x, -halfpixel.y));
+    sum += simplesample(uv - vec2(halfpixel.x, -halfpixel.y));
+
+    return sum / 8.0;
+}
+
+void main() {
+    // Uncomment to experiment with filtering out dim pixels
+    //tgt_color = filteredDownsample(uv, halfpixel);
+    tgt_color = downsample(uv, halfpixel);
 }
diff --git a/voxygen/src/render/renderer/drawer.rs b/voxygen/src/render/renderer/drawer.rs
index f0e2a301bd..4c5bc22887 100644
--- a/voxygen/src/render/renderer/drawer.rs
+++ b/voxygen/src/render/renderer/drawer.rs
@@ -277,12 +277,23 @@ impl<'frame> Drawer<'frame> {
         (0..bloom::NUM_SIZES - 1).for_each(|index| {
             let bind = &locals.bloom_binds[index].bind_group;
             let view = &views.bloom_tgts[index + 1];
-            let label = format!("downsample {}", index + 1);
+            // Do filtering out of non-bright things during the first downsample
+            let (label, pipeline) = if index == 0 {
+                (
+                    format!("downsample filtered {}", index + 1),
+                    &pipelines.bloom.downsample_filtered,
+                )
+            } else {
+                (
+                    format!("downsample {}", index + 1),
+                    &pipelines.bloom.downsample,
+                )
+            };
             run_bloom_pass(
                 bind,
                 view,
                 label,
-                &pipelines.bloom.downsample,
+                pipeline,
                 wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
             );
         });