pgraph: fix precision issues with Color(Scale)Attrib quantization

panda/src/pgraph/colorAttrib.cxx

@@ -133,17 +133,17 @@ get_hash_impl() const {
 }
 
 /**
- * Quantizes the color color to the nearest multiple of 1000, just to prevent
+ * Quantizes the flat color to the nearest multiple of 1024, just to prevent
  * runaway accumulation of only slightly-different ColorAttribs.
  */
 void ColorAttrib::
 quantize_color() {
   switch (_type) {
   case T_flat:
-    _color[0] = cfloor(_color[0] * 1000.0f + 0.5f) * 0.001f;
-    _color[1] = cfloor(_color[1] * 1000.0f + 0.5f) * 0.001f;
-    _color[2] = cfloor(_color[2] * 1000.0f + 0.5f) * 0.001f;
-    _color[3] = cfloor(_color[3] * 1000.0f + 0.5f) * 0.001f;
+    _color[0] = cfloor(_color[0] * 1024.0f + 0.5f) / 1024.0f;
+    _color[1] = cfloor(_color[1] * 1024.0f + 0.5f) / 1024.0f;
+    _color[2] = cfloor(_color[2] * 1024.0f + 0.5f) / 1024.0f;
+    _color[3] = cfloor(_color[3] * 1024.0f + 0.5f) / 1024.0f;
     break;
 
   case T_off:

panda/src/pgraph/colorScaleAttrib.cxx

@@ -230,15 +230,15 @@ invert_compose_impl(const RenderAttrib *other) const {
 }
 
 /**
- * Quantizes the color scale to the nearest multiple of 1000, just to prevent
+ * Quantizes the color scale to the nearest multiple of 1024, just to prevent
  * runaway accumulation of only slightly-different ColorScaleAttribs.
  */
 void ColorScaleAttrib::
 quantize_scale() {
-  _scale[0] = cfloor(_scale[0] * 1000.0f + 0.5f) * 0.001f;
-  _scale[1] = cfloor(_scale[1] * 1000.0f + 0.5f) * 0.001f;
-  _scale[2] = cfloor(_scale[2] * 1000.0f + 0.5f) * 0.001f;
-  _scale[3] = cfloor(_scale[3] * 1000.0f + 0.5f) * 0.001f;
+  _scale[0] = cfloor(_scale[0] * 1024.0f + 0.5f) / 1024.0f;
+  _scale[1] = cfloor(_scale[1] * 1024.0f + 0.5f) / 1024.0f;
+  _scale[2] = cfloor(_scale[2] * 1024.0f + 0.5f) / 1024.0f;
+  _scale[3] = cfloor(_scale[3] * 1024.0f + 0.5f) / 1024.0f;
 }
 
 /**