water planHEADmaster

also add local mode to build script, and fix the template's title issue
(would say index; now says the title).

3 files changed, 94 insertions, 34 deletions

diff --git a/index.md b/index.md
index 3c47448..48d90cb 100755
--- a/index.md
+++ b/index.md
@@ -1,7 +1,80 @@
 ---
-pagetitle: yummers
+title: yummers
 lang: en
 ---
+# fft water: the plan {data-date="7 Aug 2026"}
+
+About a year ago I took a stab at reimplementing Tessendorf's ocean
+water[^tessendorf]. I got some decent results, but the implementation was
+sloppy and not particularly organized. I also never implemented Bruneton's
+"geometry to BRDF" method [^bruneton], partially because the implementation was
+sloppy.
+
+I've gotten the itch to take another stab at implementing this water
+system. This time, I will try harder to proceed along principled, logical
+steps, and check my work more thoroughly along the way.
+
+I've also decided to document this process. I expect it to take a few months to
+complete this project. Hopefully in the future, these notes might help someone
+trying to implement some nice deep-ocean water in their engine/game/whatever.
+
+I'll implement this renderer as follows (this list is likely to change):
+
+* Derive a high-performance GPU-based FFT implementation on CPU.
+  * Check against a simple reference implementation of Cooley-Tukey.
+* Measure the impact of radix on the numerical precision of the FFT.
+  * Ideally, generate some graphs.
+  * Also look at the impact of float precision - 8-bit, 16-bit, etc.
+* Implement this FFT algorithm in slang + webGPU. Render unlit. Measure
+  performance.
+  * Implement image export from webGPU harness. Measure error - verify that it
+    matches expectations.
+* Generate a wave energy spectrum using Horvath's viscous shallow water wave
+  dispersion relation.
+* Generate one frame of wave displacement using slang + webGPU.
+  * Validate feature scale, energy, etc. You probably want some histograms.
+* Generate one frame of analytic normals using slang + webGPU.
+  * Validate using finite differences of the heightmap as an approximation of
+    ground truth. The two images should match within some small epsilon.
+* Generate chop and chop normals.
+  * Validate feature size and normals using finite differences (again).
+* Implement stdev (per geometry-to-brdf paper).
+  * (Note to self: this is a static image based on the energy spectrum. We
+    calculate the ddx/ddy of the offset [meters/px], then divide 2 \* pi by
+    that number to get a wave number. That is then used as the index to the
+    LUT. The LUT contains, for each wave number, the sum of the variances of
+    all waves with higher or equal wave numbers.)
+* Render a simple scene in webGPU and in Mitsuba 3.
+  * Implement a simple brdf.
+  * Implement frame export.
+  * Implement image diffing / measurement.
+  * Implement hard shadows.
+  * Implement soft shadows.
+  * Validate point lighting.
+  * Validate directional lighting.
+  * Implement and validate IBL.
+  * Implement and validate DFG LUT (energy-preserving roughness).
+  * Implement vertex deformation and normals using baked heightmap & tangents.
+    Validate against Mitsuba.
+    * Make a new scene with a highly subdivided quad.
+* Port to Unity.
+  * Implement tooling to blit a texture through a RenderTexture using a shader.
+    * Automation should generate quads, materials, and rendertextures on behalf
+      of the user.
+  * Port compute shader to shaderlab pixel shader. Validate.
+  * Port lit shader to shaderlab.
+    * Sample scene, frame export, exhaustive validation... the works.
+  * Validate point, directional, and IBL.
+  * Add light volumes.
+  * Add LTCGI.
+
+So... yeah. A lot of work. I'll get started tomorrow!
+
+---
+
+[^tessendorf]: Tessendorf, Jerry. *Simulating Ocean Water*. 2004. [PDF](https://people.computing.clemson.edu/~jtessen/reports/papers_files/coursenotes2004.pdf).
+[^bruneton]: Bruneton, Eric et. al. *Real-time Realistic Ocean Lighting using Seamless Transitions from Geometry to BRDF*. 2010. [PDF](https://inria.hal.science/inria-00443630/PDF/article-1.pdf).
+
 # how do you evenly tile a column? {data-date="12 Jul 2026"}
 
 While walking through town the other day, I saw a pillar that looks a bit like this:
diff --git a/make_html b/make_html
index fe42448..fdc8133 100755
--- a/make_html
+++ b/make_html
@@ -2,13 +2,18 @@
 
 MARKDOWN_IN="$1"
 [ -z "$MARKDOWN_IN" ] && { echo "Script requires one markdown argument."; exit 1; }
+if [ $# -eq 2 ]; then
+  LOCAL_MODE=1
+fi
 
 set -o errexit
 set -o xtrace
 
 OUTPUT_DIR="site_generated"
-[ -d "$OUTPUT_DIR" ] && rm -r "$OUTPUT_DIR"
-mkdir "$OUTPUT_DIR"
+[ ! $LOCAL_MODE ] && [ -d "$OUTPUT_DIR" ] && rm -r "$OUTPUT_DIR"
+if [ ! -d "$OUTPUT_DIR" ]; then
+  mkdir "$OUTPUT_DIR"
+fi
 
 pandoc \
   --mathml \
@@ -20,6 +25,12 @@ pandoc \
   -o "$OUTPUT_DIR/site.zip" \
   "$MARKDOWN_IN"
 
+if [ $# -eq 2 ]; then
+  # Local mode
+  unzip -o "$OUTPUT_DIR/site.zip" -d "$OUTPUT_DIR"
+  exit
+fi
+
 unzip -o "$OUTPUT_DIR/site.zip" -d /var/www/html/
 cp -r vr_assets /var/www/html/
 cp -r images /var/www/html/
diff --git a/template.html b/template.html
index a0cfc1a..7567942 100755
--- a/template.html
+++ b/template.html
@@ -104,6 +104,13 @@ $endif$
       color: var(--foreground-color);
       border-left: 4px solid var(--current-line-color);
     }
+    /* numbered citations rendered from Markdown footnotes */
+    .footnote-ref sup {
+      font-size: inherit;
+      vertical-align: baseline;
+    }
+    .footnote-ref sup::before { content: "["; }
+    .footnote-ref sup::after { content: "]"; }
     ::selection {
       background-color: var(--selection-color);
     }
@@ -160,26 +167,6 @@ $endif$
 $for(include-before)$
 $include-before$
 $endfor$
-$if(title)$
-  <header id="title-block-header">
-  <h1 class="title">$title$</h1>
-  $if(subtitle)$
-    <p class="subtitle">$subtitle$</p>
-  $endif$
-  $for(author)$
-    <p class="author">$author$</p>
-  $endfor$
-  $if(date)$
-    <p class="date">$date$</p>
-  $endif$
-  $if(abstract)$
-    <div class="abstract">
-    <div class="abstract-title">$abstract-title$</div>
-    $abstract$
-    </div>
-  $endif$
-  </header>
-$endif$
 $if(top)$
 $body$
   <p><a href="/">back to main page</a></p>
@@ -202,17 +189,6 @@ $else$
   be able to quickly assess quality regardless of how the code is made.
   </p>
   <p>
-  core beliefs:
-  <ol>
-    <li>information should be free;</li>
-    <li>human-caused climate change is real, significant, and solvable;</li>
-    <li>passive acceptance of cruelty is complicity;</li>
-    <li>trans rights are human rights;</li>
-    <li>the web is a vast sea made of individuals with feelings;</li>
-    <li>your actions matter.</li>
-  </ol>
-  </p>
-  <p>
   links:
   <ul>
     <li><a href="https://git.yummers.dev">git server</a></li>