Update Lut.js

If in the example `webgl_geometry_colors_lookuptable` I change 
https://github.com/mrdoob/three.js/blob/dev/examples/webgl_geometry_colors_lookuptable.html#L183 to `lut.setMin( -1000 );`, the scale goes from 0 to 3000, not from -1000 to 2000. Anything else than 0 as minimum scale value is broken. This pull request negative

examples/js/math/Lut.js

@@ -369,7 +369,7 @@ THREE.Lut.prototype = {
 
 			for ( var i = 0; i < this.legend.labels.ticks; i ++ ) {
 
-				var value = ( this.maxV - this.minV ) / ( this.legend.labels.ticks - 1  ) * i ;
+				var value = ( this.maxV - this.minV ) / ( this.legend.labels.ticks - 1  ) * i + this.minV;
 
 				if ( callback ) {
 
@@ -418,7 +418,7 @@ THREE.Lut.prototype = {
 
 				if ( this.legend.layout == 'vertical' ) {
 
-					var position = bottomPositionY + ( topPositionY - bottomPositionY ) * ( value / ( this.maxV - this.minV ) );
+					var position = bottomPositionY + ( topPositionY - bottomPositionY ) * ( ( value - this.minV ) / ( this.maxV - this.minV ) );
 
 					spriteTick.position.set( this.legend.position.x + ( this.legend.dimensions.width * 2.7 ), position, this.legend.position.z );
 
@@ -426,7 +426,7 @@ THREE.Lut.prototype = {
 
 				if ( this.legend.layout == 'horizontal' ) {
 
-					var position = bottomPositionX + ( topPositionX - bottomPositionX ) * ( value / ( this.maxV - this.minV ) );
+					var position = bottomPositionX + ( topPositionX - bottomPositionX ) * ( ( value - this.minV ) / ( this.maxV - this.minV ) );
 
 					if ( this.legend.labels.ticks > 5 ) {
 
@@ -457,7 +457,7 @@ THREE.Lut.prototype = {
 
 				if ( this.legend.layout == 'vertical' ) {
 
-					var linePosition = ( this.legend.position.y - ( this.legend.dimensions.height * 0.5 ) + 0.01 ) + ( this.legend.dimensions.height ) * ( value / ( this.maxV - this.minV ) * 0.99 );
+					var linePosition = ( this.legend.position.y - ( this.legend.dimensions.height * 0.5 ) + 0.01 ) + ( this.legend.dimensions.height ) * ( ( value - this.minV ) / ( this.maxV - this.minV ) * 0.99 );
 
 					geometry.vertices.push( new THREE.Vector3( this.legend.position.x + this.legend.dimensions.width * 0.55, linePosition, this.legend.position.z  ) );
 
@@ -467,7 +467,7 @@ THREE.Lut.prototype = {
 
 				if ( this.legend.layout == 'horizontal' ) {
 
-					var linePosition = ( this.legend.position.x - ( this.legend.dimensions.height * 0.5 ) + 0.01 ) + ( this.legend.dimensions.height ) * ( value / ( this.maxV - this.minV ) * 0.99 );
+					var linePosition = ( this.legend.position.x - ( this.legend.dimensions.height * 0.5 ) + 0.01 ) + ( this.legend.dimensions.height ) * ( ( value - this.minV ) / ( this.maxV - this.minV ) * 0.99 );
 
 					geometry.vertices.push( new THREE.Vector3( linePosition, this.legend.position.y - this.legend.dimensions.width * 0.55, this.legend.position.z  ) );