From f2a54b31415904ae3ece83770accfdcfaabc471f Mon Sep 17 00:00:00 2001
From: Rezmason <jeremysachs@rezmason.net>
Date: Wed, 27 Oct 2021 20:00:39 -0700
Subject: [PATCH] A little bit of shader variable renaming and const
 declaration during a walkthrough of the existing code on-stream

---
 js/webgpu_main.js           |  4 +++-
 shaders/rainRenderPass.wgsl | 14 +++++++-------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/js/webgpu_main.js b/js/webgpu_main.js
index c057ea6..182521e 100644
--- a/js/webgpu_main.js
+++ b/js/webgpu_main.js
@@ -32,6 +32,8 @@ const loadTexture = async (device, url) => {
 export default async (canvas, config) => {
 	console.log(config);
 
+	const NUM_VERTICES_PER_QUAD = 6;
+
 	const numColumns = config.numColumns;
 	const numRows = config.numColumns;
 
@@ -183,7 +185,7 @@ export default async (canvas, config) => {
 		bundleEncoder.setBindGroup(index, bindGroup);
 	});
 	const numQuads = numColumns * numRows;
-	bundleEncoder.draw(6 * numQuads, 1, 0, 0);
+	bundleEncoder.draw(NUM_VERTICES_PER_QUAD * numQuads, 1, 0, 0);
 	const renderBundles = [bundleEncoder.finish()];
 
 	let frame = 0;
diff --git a/shaders/rainRenderPass.wgsl b/shaders/rainRenderPass.wgsl
index 995c62f..8325c77 100644
--- a/shaders/rainRenderPass.wgsl
+++ b/shaders/rainRenderPass.wgsl
@@ -1,5 +1,6 @@
+let NUM_VERTICES_PER_QUAD:i32 = 6;
 let PI:f32 = 3.14159265359;
-let TWO_PI:f32 = 6.28318530718;
+let TWO_PI:f32 = 6.28318530718; // No, I'm not using Tau.
 
 [[block]] struct Uniforms {
 	numColumns: i32;
@@ -15,7 +16,7 @@ let TWO_PI:f32 = 6.28318530718;
 [[group(1), binding(2)]] var msdfTexture: texture_2d<f32>;
 
 [[block]] struct TimeUniforms {
-	time: i32;
+	now: i32;
 	frame: i32;
 };
 [[group(2), binding(0)]] var<uniform> timeUniforms:TimeUniforms;
@@ -30,11 +31,11 @@ struct VertexOutput {
 [[stage(vertex)]] fn vertMain([[builtin(vertex_index)]] VertexIndex:u32) -> VertexOutput {
 
 	var i = i32(VertexIndex);
-	var quadIndex = i / 6;
+	var quadIndex = i / NUM_VERTICES_PER_QUAD;
 
 	var cornerPosition = vec2<f32>(
 		f32(i % 2),
-		f32(((i + 1) % 6 / 3))
+		f32(((i + 1) % NUM_VERTICES_PER_QUAD / 3))
 	);
 
 	var x = uniforms.numColumns;
@@ -49,7 +50,6 @@ struct VertexOutput {
 		f32(uniforms.numRows)
 	);
 	position = 1.0 - position * 2.0;
-	// position.x = position.x + f32(quadIndex) * 0.01;
 
 	return VertexOutput(
 		vec4<f32>(position, 1.0, 1.0),
@@ -61,9 +61,9 @@ struct VertexOutput {
 
 [[stage(fragment)]] fn fragMain([[location(0)]] UV:vec2<f32>) -> [[location(0)]] vec4<f32> {
 	var msdf:vec4<f32> = textureSample(msdfTexture, msdfSampler, UV / f32(msdfUniforms.numColumns));
-	// msdf.b = msdf.b * (sin(f32(timeUniforms.time) / 1000.0 * TWO_PI) * 0.5 + 0.5);
+	// msdf.b = msdf.b * (sin(f32(timeUniforms.now) / 1000.0 * TWO_PI) * 0.5 + 0.5);
 	msdf.b = msdf.b * f32(timeUniforms.frame / 60 % 2);
-	var time = timeUniforms.time;
+	var now = timeUniforms.now;
 
 	return msdf;
 }