From 49cb3cb98b8c92fcbcc0a53a1e072c1f9372dcbf Mon Sep 17 00:00:00 2001
From: Ken Russell <kbrussel@alum.mit.edu>
Date: Thu, 16 Dec 2021 21:57:16 -0800
Subject: [PATCH] Clarify behavior of POINTS draws when gl_PointSize is
 unassigned.

These are guaranteed by the WebGL API to produce no output.
---
 specs/latest/1.0/index.html | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/specs/latest/1.0/index.html b/specs/latest/1.0/index.html
index 9c77dd32c9..30337f6079 100644
--- a/specs/latest/1.0/index.html
+++ b/specs/latest/1.0/index.html
@@ -4455,6 +4455,28 @@ <h3>Wide point primitive clipping</h3>
     </p>
 </div>
 
+<h3>gl_PointSize must be set in vertex shader when drawing POINTS</h3>
+
+<p>
+If <code>POINTS</code> primitives are drawn, then the vertex shader for the currently bound program
+must set the built-in output variable <code>gl_PointSize</code>, or the draw will have no effect.
+</p>
+
+<div class="note rationale">
+<p>
+The OpenGL ES and OpenGL GLSL ES specifications define that if the built-in vertex shader output
+variable <code>gl_PointSize</code> is not written to, then its value is undefined in later shader
+stages. As a consequence, in these specifications, it is undefined whether the draw has an effect.
+</p>
+
+<p>
+
+The WebGL API clarifies this behavior by guaranteeing that such draws have no effect. All of the
+validation for the draw operation, including generation of any errors, is still performed.
+</p>
+</div>
+
+
 <!-- ======================================================================================================= -->
 
     <h2>References</h2>