2015-04-08 20:02 GMT+02:00 karl ramberg karlramberg@gmail.com:
Confirmed.
Karl
On Wed, Apr 8, 2015 at 5:33 PM, Nicolai Hess nicolaihess@web.de wrote:
In order to reproduce it, draw a rectangle with radial gradient fill, with direction and normal, both of length 1.
This is not the reason why it crashes. It happens for other values as well:
|form canvas fill direction normal| direction := 4@0. normal := 0@2. form := Form extent:300@300 depth:32. canvas := form getCanvas. fill := GradientFillStyle new colorRamp:{0 -> Color white . 0.5 -> Color green . 1 -> Color blue};origin:400@400 ;direction:direction;normal:normal;radial:true;yourself. canvas fillRectangle: (0@0 extent:800@800) fillStyle: fill. Display getCanvas drawImage: form at: 300@300
This uses a different value for direction and normal and the fill is defined for a larger area (800x800) -> CRASH
Maybe, this is a rare bug, because, normally you don't create a small gradient t o fill a large area. But a vm crash is not nice, I would like to get this fixed.
I am not sure what is the exact cause, but it may come from a signed integer overflwo, It looks like Balloon uses fixed point arithmetik (binary scaling). This fixed point representation (16.16 bit fixed point represented in a 32 integer) tend to overflow, especially for operations like computing the squared length of a vector x*x+y*y -> overflow -> result is a negative number.
Possible solutions: downscale prior to the multiplication -> lost of precision use a larger datatype for intermediate results.
It looks like B2D uses the first option (look at senders of accurateLengthOfwith and squaredLenghtOfwith Maybe there is something wrong with the other code that multiplies the values, or the 16.16 bit fixed point is just not large enough for some fills?
Any ideas?
Nicolai
This one works (no vm crash): |form canvas fill direction normal| direction := 1@0. normal := 0@0. form := Form extent:300@300 depth:32. canvas := form getCanvas. fill := GradientFillStyle new colorRamp:{0 -> Color white . 0.5 -> Color green . 1 -> Color blue};origin:150@150 ;direction:direction;normal:normal;radial:true;yourself. canvas fillRectangle: (50@50 extent:200@200) fillStyle: fill. Display getCanvas drawImage: form at: 300@300.
direction := 1@0. normal := 0@0. -> OK
direction := 0@0. normal := 0@1. -> OK
direction := 1@0. normal := 0@1. -> VM-Crash (Pharo and Squeak)
Pharo: VM Version: Cog VM 4.0.0 (release) from Feb 16 2015 Compiler: gcc 4.6.2 Interpreter Build: NBCoInterpreter NativeBoost-CogPlugin-EstebanLorenzano.21 uuid: 4d9b9bdf-2dfa-4c0b-99eb-5b110dadc697 Feb 16 2015 Cogit Build: NBCogit NativeBoost-CogPlugin-EstebanLorenzano.21 uuid: 4d9b9bdf-2dfa-4c0b-99eb-5b110dadc697 Feb 16 2015 Source Version: https://github.com/pharo-project/pharo-vm.git Commit: 55fbd0b0279998a4a33852f5afb3d213986cc3ae Date: 2015-02-16 17:54:00 +0100 By: Esteban Lorenzano estebanlm@gmail.com Jenkins build #14895
Current byte code: -1 Primitive index: 117 Smalltalk stack dump: 0x24c830 M BalloonEngine>copyLoopFaster 0x6b09b80: a(n) BalloonEngine 0x24c848 M BalloonEngine>copyBits 0x6b09b80: a(n) BalloonEngine 0x24c860 M BalloonEngine>postFlushIfNeeded 0x6b09b80: a(n) BalloonEngine 0x24c884 I BalloonEngine>drawRectangle:fill:borderWidth:borderColor:transform: 0x6b09b80: a(n) BalloonEngine 0x24c8b8 I BalloonCanvas>drawRectangle:color:borderWidth:borderColor: 0x6b099c0: a(n) BalloonCanvas 0x24c8e8 I BalloonCanvas>fillRectangle:basicFillStyle: 0x6b099c0: a(n) BalloonCanvas
Squeak: VM Version: Cog VM 4.0.0 (release) from Aug 22 2013 Compiler: gcc 3.4.4 (cygming special, gdc 0.12, using dmd 0.125) Interpreter Build: CoInterpreter VMMaker.oscog-eem.331 uuid: 37d2e4b0-2f37-4e2d-8313-c63637785e59 Aug 22 2013 Cogit Build: StackToRegisterMappingCogit VMMaker.oscog-eem.333 uuid: 84da9cb8-7f30-4cb7-b4fb-239a11f63b54 Aug 22 2013 Source Version: VM: r2776 http://www.squeakvm.org/svn/squeak/branches/Cog Plugins: r2545 http://squeakvm.org/svn/squeak/trunk/platforms/Cross/plugins
Current byte code: -1 Primitive index: 117
nicolai