From 3d94eaf8a7f764bbd78816d7f39037d5d90f8383 Mon Sep 17 00:00:00 2001
From: Dominic Prior <dominicprior42@gmail.com>
Date: Thu, 8 Sep 2022 11:08:57 +0100
Subject: [PATCH] Always call vertexAttribDivisor

Previously, if the divisor property was absent, the
gl.vertexAttribDivisor call would be omitted, which
caused the divisor value to be inherited from the
previous program.

With this change, an absent divisor causes an explicit
call to gl.vertexAttribDivisor with parameter zero.

Note this is a breaking change if people have been
deliberately or accidentally carrying divisor values
forward from one program to the next.
---
 src/attributes.js |  4 ++--
 src/programs.js   | 16 ++++------------
 2 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/src/attributes.js b/src/attributes.js
index f1012b18..7a8b2f4d 100644
--- a/src/attributes.js
+++ b/src/attributes.js
@@ -198,7 +198,7 @@ function makeTypedArray(array, name) {
  * @property {boolean} [normalize] whether or not to normalize the data. Default = false
  * @property {number} [offset] offset into buffer in bytes. Default = 0
  * @property {number} [stride] the stride in bytes per element. Default = 0
- * @property {number} [divisor] the divisor in instances. Default = undefined. Note: undefined = don't call gl.vertexAttribDivisor
+ * @property {number} [divisor] the divisor in instances. Default = 0
  *    where as anything else = do call it with this value
  * @property {WebGLBuffer} buffer the buffer that contains the data for this attribute
  * @property {number} [drawType] the draw type passed to gl.bufferData. Default = gl.STATIC_DRAW
@@ -221,7 +221,7 @@ function makeTypedArray(array, name) {
  * @property {boolean} [normalize] normalize for `vertexAttribPointer`. Default is true if type is `Int8Array` or `Uint8Array` otherwise false.
  * @property {number} [stride] stride for `vertexAttribPointer`. Default = 0
  * @property {number} [offset] offset for `vertexAttribPointer`. Default = 0
- * @property {number} [divisor] divisor for `vertexAttribDivisor`. Default = undefined. Note: undefined = don't call gl.vertexAttribDivisor
+ * @property {number} [divisor] divisor for `vertexAttribDivisor`. Default = 0
  *    where as anything else = do call it with this value
  * @property {string} [attrib] name of attribute this array maps to. Defaults to same name as array prefixed by the default attribPrefix.
  * @property {string} [name] synonym for `attrib`.
diff --git a/src/programs.js b/src/programs.js
index 97e83d07..9e899f63 100644
--- a/src/programs.js
+++ b/src/programs.js
@@ -395,9 +395,7 @@ function floatAttribSetter(gl, index) {
       gl.enableVertexAttribArray(index);
       gl.vertexAttribPointer(
           index, b.numComponents || b.size, b.type || FLOAT, b.normalize || false, b.stride || 0, b.offset || 0);
-      if (b.divisor !== undefined) {
-        gl.vertexAttribDivisor(index, b.divisor);
-      }
+      gl.vertexAttribDivisor(index, b.divisor || 0);
     }
   };
 }
@@ -416,9 +414,7 @@ function intAttribSetter(gl, index) {
       gl.enableVertexAttribArray(index);
       gl.vertexAttribIPointer(
           index, b.numComponents || b.size, b.type || INT, b.stride || 0, b.offset || 0);
-      if (b.divisor !== undefined) {
-        gl.vertexAttribDivisor(index, b.divisor);
-      }
+      gl.vertexAttribDivisor(index, b.divisor || 0);
     }
   };
 }
@@ -437,9 +433,7 @@ function uintAttribSetter(gl, index) {
       gl.enableVertexAttribArray(index);
       gl.vertexAttribIPointer(
           index, b.numComponents || b.size, b.type || UNSIGNED_INT, b.stride || 0, b.offset || 0);
-      if (b.divisor !== undefined) {
-        gl.vertexAttribDivisor(index, b.divisor);
-      }
+      gl.vertexAttribDivisor(index, b.divisor || 0);
     }
   };
 }
@@ -462,9 +456,7 @@ function matAttribSetter(gl, index, typeInfo) {
       gl.enableVertexAttribArray(index + i);
       gl.vertexAttribPointer(
           index + i, size, type, normalize, stride, offset + rowOffset * i);
-      if (b.divisor !== undefined) {
-        gl.vertexAttribDivisor(index + i, b.divisor);
-      }
+      gl.vertexAttribDivisor(index + i, b.divisor || 0);
     }
   };
 }