[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [37329] trunk/blender/source/blender/ editors/interface/interface.c: use a better method for finding the precision to use for float buttons, about 4x faster to calculate and will show for eg, 0.0108 rather than 0.01 , but 0.0100001 still displays as 0.01.

[Campbell Barton]

Revision: 37329
          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=37329
Author:   campbellbarton
Date:     2011-06-09 07:40:30 +0000 (Thu, 09 Jun 2011)
Log Message:
-----------
use a better method for finding the precision to use for float buttons, about 4x faster to calculate and will show for eg, 0.0108 rather than 0.01, but 0.0100001 still displays as 0.01.

Modified Paths:
--------------
    trunk/blender/source/blender/editors/interface/interface.c

Modified: trunk/blender/source/blender/editors/interface/interface.c
===================================================================
--- trunk/blender/source/blender/editors/interface/interface.c	2011-06-09 04:28:53 UTC (rev 37328)
+++ trunk/blender/source/blender/editors/interface/interface.c	2011-06-09 07:40:30 UTC (rev 37329)
@@ -74,6 +74,9 @@
 #define MENU_ITEM_HEIGHT	20
 #define MENU_SEP_HEIGHT		6
 
+#define PRECISION_FLOAT_MAX 7
+#define PRECISION_FLOAT_MAX_POW 10000000 /* pow(10, PRECISION_FLOAT_MAX)  */
+
 /* 
  * a full doc with API notes can be found in bf-blender/trunk/blender/doc/guides/interface_API.txt
  * 
@@ -463,27 +466,39 @@
 	 * _but_, this is only for small values si 10.0001 will not get
 	 * the same treatment */
 	if(value != 0.0 && (value= ABS(value)) < 0.1) {
-		double prec_d= -(log10(value));
-		double prec_d_floor = floor(prec_d + FLT_EPSILON);
-		int test_prec= (int)prec_d_floor;
+		int value_i= (int)((value * PRECISION_FLOAT_MAX_POW) + 0.5);
+		if(value_i != 0) {
+			const int prec_span= 3; /* show: 0.01001, 5 would allow 0.0100001 for eg. */
+			int test_prec;
+			int prec_min= -1;
+			int dec_flag= 0;
+			int i= PRECISION_FLOAT_MAX;
+			while(i && value_i) {
+				if(value_i % 10) {
+					dec_flag |= 1<<i;
+					prec_min= i;
+				}
+				value_i /= 10;
+				i--;
+			}
 
-		/* this check is so 0.00016 from isnt rounded to 0.0001 */
-		if(prec_d - prec_d_floor > FLT_EPSILON) { /* not ending with a .0~001 */
-			/* check if a second decimal place is needed 0.00015 for eg. */
-			if(double_round(value, test_prec + 1) - double_round(value, test_prec + 2) != 0.0) {
-				test_prec += 2;
+			/* even though its a small value, if the second last digit is not 0, use it */
+			test_prec = prec_min;
+
+			dec_flag= (dec_flag >> (prec_min + 1)) & ((1 << prec_span) - 1);
+
+			while(dec_flag) {
+				test_prec++;
+				dec_flag = dec_flag >> 1;
 			}
-			else {
-				test_prec += 1;
+
+			if(test_prec > prec) {
+				prec= test_prec;
 			}
 		}
-
-		if(test_prec > prec && test_prec <= 7) {
-			prec= test_prec;
-		}
 	}
 
-	CLAMP(prec, 1, 7);
+	CLAMP(prec, 1, PRECISION_FLOAT_MAX);
 
 	return prec;
 }
@@ -1484,8 +1499,8 @@
 	if(scene->unit.scale_length<0.0001f) scene->unit.scale_length= 1.0f; // XXX do_versions
 
 	/* Sanity checks */
-	if(precision>7)		precision= 7;
-	else if(precision==0)	precision= 2;
+	if(precision > PRECISION_FLOAT_MAX)	precision= PRECISION_FLOAT_MAX;
+	else if(precision==0)				precision= 2;
 
 	bUnit_AsString(str, len_max, ui_get_but_scale_unit(but, value), precision, scene->unit.system, unit_type>>16, do_split, pad);
 }