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From: kartik subramanian <subramaniam.kartik@gmail.com>
Date: Thu, Jun 4, 2009 at 4:53 PM
Subject:
To: catchgokul1.blender@blogger.com

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SCJP Certified.

Update on the Ammonia Experiment

After months of hardwork learning the BGE (Blender Game Engine) and the Fluid Simulation , it is very sad to find out that the blender game engine which uses the bullet physics library (currently bullet 2.70) does not have support for particles and fliud simulations . Basically the physics library doesnt know how to calculate the CPU intensive calculations for collisions of softbody and rigid bodies with fluids. So the whole interactive nature of the experiment is on hold till we figure out a way to do it.
now we are continuing with making a video of the experiment atleast.
The following is the way we plan to do it :

Since we have multiple fliud simulations and different events , we decided it would be easier to split the animation into 2 scenes.

1st Scene where we introduce the apparatus and the water in the trough is baked :


2nd Scene where 3 things happen , water in the trough reduces after the injection is pressed following which the water fountain happens.



now both these scenes are separately animated into avi files.
then using the blenders video sequence editor , we plan to complete the animation.



- Gokul

VIDEO SEQUENCE EDITOR

Well you all must have read gokul's mail regarding our doubt in fluid simulation. To quickly bring everyone upto speed - our problem was that we did not know how to bring additional objects into the ongoing animation from a particular(desired) frame.

I was reading to find a solution to our problem and i came across the video sequence editor. It is basically an inbuilt feature in blender which is analogous(if not better) to windows movie maker.
It allows you to split, combine, slow down,etc etc basically anything to do with making a movie.

So i used this feature to solve the "two different coloured ico spheres falling into a container one after the other(basically after desired frames)" problem. The animation is basic and i have not given any subsurf or any textures or tried to work on the lighting. It is solely to illustrate the solution.

The screenshot of the video sequence editor is shown below.
-The top right portion displays the preview
-The top left portion is the ipo curve editor
-The middle portion is the video sequence editor
-The bottom portion displays the timeline



You have to go to the "add" in the video sequence editor portion of the screen to add either an image, or movie, or your baked files. So there is alot of flexibility and alot of options. You can play your file in slow motion by setting the frames/sec field in the "playback" option.

The final output can be in a number of formats as always. The important thing to remember is that in the "render buttons" the "do sequence" option needs to be selected.


The final animation:

Fountain Experiment's Model

After a week long effort towards modelling, we have at last satisfactorily finished the modelling aspect of the Ammonia Fountain Experiment.
While modelling we faced various problems and tried solving them in the ways as described ahead, but if someone knows the exact reason of these problems and how to solve them in a more satisfactory manner, please feel free to notify us. Here are the problems:
1) We had already made 1 hole in the cork. In order to make the 2nd hole, we decided instead of actually modelling it, we could just delete half of the pre-existing cork and then mirror it. This seemed like a simple solution until the mirror effect started giving us problems as the new mirrored portion was overlapping the already existing part. We had to actually make the new mirrored part a separate object, select its faces manually rotate it to fit de existing half and then join the two objects.
2) The glass material that we are using gave us some problems. The cork and the glass pipe that are inside the flask were not visible and black in colour. After some R&D on Google, we found out that by switching the shadow tab off in the materials panel of an object disallows it to have any shadows cast on it. Hence we switched it off for the cork and it stopped receiving the glass flasks shadow and as you can see in the final rendered image, it looks quite fine.
3) Again similar issue with the wooden table and the glass dish below. We had to actually cut the wooden table's part under the dish, make a new object (plane) in its place and assign it the no shadow receiving property as we wanted the rest of the wooden table to receive shadows.

Thankfully we managed to fix these issues satisfactorily and here is the final rendered model and its corresponding mesh images in blender.

Here is the list of objects modelled:
1) Round bottomed flask
2) Water dish
3) Two holed cork
4) Glass Pipe
5) Syringe
6) Stand

Also the materials that we have used are make do and will be changed or modified if required. Please go through the model and post your inputs.

Problems with fluid animation in fountain experiment !!!

After 6-7 hours of agony we have come to the conlusion that , we are dealing with an area of blender which has little documentation , loads of bugs , slow development cycle and very useful to our experiment.

Fluid simulation seems to be working differently on different machines , differently in different versions and also there are some settings which we still have to understand.
For example each time the ratio of the total volume of the fluid in the simulation to the total volume of the cuboid (domain) goes below a certain threshhold , the baking doesnt happen. Now this is a major bottleneck to our project. Either we bake it in a different scene and use it in the complicated scene or we learn how to break down the animation into multiple domains to simplify.
the following are the bugs we have come across while playing around with fluid simulations :

a) viewport doesnt show properly the mesh data.
b) obstacles when intersecting or too close to one an another , baking doesnt work.
c) init shell doesnt work when objects are too complicated.
d) sometimes obstacles dun behave as proper obstackles.

the following images shows the bugs we discovered :







So now our model with the flask and jet through cork wasnt working with fluids , no matter what we did. So we tried to animate the fluid without the model , just using a dummy model in a different blender scene. we could manage to bake it after a lot of trial and error and we hope to get the fluid animation from this scene to work in our original scene. the following are the screenshots of the new dummy scene we made to make the fluid work.




hope somebody can shed light on why blender doesnt bake fluids in our original scene. Also if some one can find any link or ebook which has documentation on blender fluid simulations. any help would be great.

regards
gokul menon

Ammonia Experiment Storyboard

We prepared the story board for the experiment as sir had told us to do.
made it into a ppt , have embedded it here as follows.

Ammonia Fountain EXP Modelling

Gokul & I, alongwith learning the python tutorials decided to start the modelling of the selected experiment. We decided to model the glass flask, the glass jet and the rubber cork without the appropriate textures for the day. We finished the modelling and thought we should try baking a scene where the water goes through the glass jet and comes out into the glass flask. After several hours of trying the same, we did not manage to do so. We are experiencing the same problem we faced last sem. The problem is the water does not pass through the small glass jet. It either does not bake or does not obey laws of physics. If anyone has a solution please PLEASE let us know as we intend on finishing the modelling soon and wish to start the animation.

The following are the pictures of our work today.

Water falling in a glass bowl (revisited)

I remember doing my 1st blender fluid simulation of a water sphere falling inside a water mug. its been a long time since then and i have decided to go back to basics for the ammonia experiment. I just realised that i can use single walled meshes for my flasks and trough instead of the agonizingly complex double walled mesh we are used to creating as blender isnt able to calculate the necessary fluid simulation co-ordinates when fluid is to flow inside or outside the object. But if the init shell option is turned on for an object acting as an obstacle then this difficulty can be overcome. That is what i have done in the following simulation. i made a simple uv sphere , cut it open in half and let it remain a single walled semi circular shapped flask. then i poured fluid into it. the uv sphere acts as obstacle with init shell option turned on. the domain is as usual a big cube. the following picture shows the mesh :
the result is as shown in the video :

this is an interesting development i believe , because if we manage to work with single walled meshes , then our work is reduced to half. its like suppose the project was to one has to count all the leaves in a given tree , then i guess this discovery is analogous to that of finding out that the tree is perfectly symmetrical along one of the axis which efectively reduces the work by half.

regards gokul

Fountain Experiment Script

SCENE 1: APPARATUS INTRODUCTION
Step 1: Introduce Flask, 500 cm3 or 1 dm3 which is completely dry and filled with ammonia
Step 2: Introduce Two-holed rubber stopper to fit the flask fitted with a glass jet
Step 3: Introduce Plastic syringe (10 cm3) half filled with water.
Step 4: Introduce Trough or large beaker which can hold more water than the flask and filled with a mixture of water and an acid-alkali indicator (e.g. Universal indicator)
Step 5: White board or sheet of card to act as a background to improve visibility

SCENE 2: APPARATUS SETTING
Step 1: show inverted flask on who’s entrance the two way rubber stopper has been placed and the syringe has been placed inside the 2nd hole of the rubber stopper. The end of the glass jet with the smaller bore is show inside the flask and the one with the bigger bore is kept free for the moment.
Step 2: The end of the jet with the bigger bore is placed dipped inside the liquid in the trough as shown in the diagram and the white background is placed behind this whole arrangement.




SCENE 3: THE DEMONSTRATION
Step 1: Use the syringe to squirt a few cm3 of water into the flask and gently swirl to dissolve some of the ammonia gas.
Step 2: As the gas dissolves, a partial vacuum forms inside the flask and the external air pressure will force water up the tube and through the jet - forming a fountain (see first diagram). The ammonia gas dissolves in the water emerging from the jet and the indicator changes colour.
Step 3: The fountain continues for some minutes, depending on the size of the flask and the width of the jet. When the fountain finishes, a bubble of gas remains. This is air and its volume gives an indication of how well the flask was originally filled.

Fountain Experiment Schedule

Tentative schedule for the fountain experiment (class 10) is as follows :

28th January - Script of the Experiment
7th February – Python Study
14th February - Modeling of Objects
21st February – Fluid Engine .
28th February – Game Engine and scripting.
7th March – Texturing of Objects.
28th March - Lighting and Camera.
5th April - Rendering & Testing of Experiment.
15th April - Final Product.

Camera static problem !!!

From Day 1 of making animations in blender..we have faced this issue of the camera beeing static object in our scene..well i read some wiki blender tutorials to figure out ways for the camera to move...this is a small demonstration of the way to do it..

step 1 : make a beizer circle..in editing tools(f6) , make path length to a suitable number..say 400 or 500.

step 2: go to ipo curve window n in object menu..select path.press up or down key

step 2a:you will notice a green line..thats the timeline..x axis time..y axis is speed.

step2b: now go to 0,0 and press alt+right click to fix a point.

step2c: now go to point 300,1 and alt+right click to fix 2nd point.

step 3: click on "curve" in ipo menu to change interpolation to linear ,make extended mode to cyclic

step 4 :place camera on the cirumferance of the beizer circle

step 5: select circle n camera together n press ctr+P

step 6: from drop down menu select follow path

and your set..press right arrow key to check the camera following the curve

here's a scrshot

here's the final video :

-Gokul

ps. if the instructions werent clear .please call me or mail me..il be able to help..

SIMPLE HAND PUMP COMPLETE

We are happy to announce that we have finished one complete animation from http://www.arvindguptatoys.com/ as Shridhar Sir had asked us. We are uploading the screenshots and the video. We are simultaneously working on other similar animations and will put them up in due course time.


Integrating three different dynamic objects namely:
1. Movement of handle in game engine
2. Movement of water inside bucket
3. Movement of water from nozzle



Before rendering



After rendering

Rendered Video!!!!

Ps: Incase video doesnt play check yahoo group for blend files and video

-Gokul and Karan

Game Engine With Liquid Simulation !!! CRACKED

This is the video rendered after cracking the problem we had , which prevented us from using both the game engine and the fluid simulation module in blender.

this video shows both game engine working and the fluid simulation working simultaneosly.

this is a big break through for us and hopefully we can now work faster with our project..

- Gokul

Game Engine

Past 2 weeks ive been dabbling with the game engine , since we would be using it in our interactive part of the project.

i have managed to export a simple exe file which when made to run of the blender installation directory works perfectly like any other exe. i have provided the download link of the exe file below, one can download it , place it in ur blender installation directory on your hard drive and just double click it. Once the game window opens..then press space to make the sphere hit the dominos. One can press space indefinete no. of times.

ive provided some images as well

here they are

download link of exe file : http://rapidshare.de/files/40687158/domino.exe.html

i am working on making some more exe in order to fully understand the power of the game engine of blender

cheers

Gokul

Making glass Pipes In 5 minutes

i came across this technique by chance , i was playing around with the bazier curve and suddenly i saw the option of bavel...well it basically spins the curve across the baveld object. So i spun a bazier curve along a bazier circle and Voila ! i got a pipe. By applying the material effects for glass in 2 minutes i had made a glass pipe. By using the Extrude option i could change the size and shape of the pipe. i am posting the image of the rendered file. I shall post the .blend file on yahoo groups once i make a better one.

here is the image

posted by Gokul

regards

Water in a Glass Tank

Adding to the posts by karan...this is the final product of all the hours of labouring today. i have added the rapidshare download link to all those who cannot access youtube. the rendered image

the video :

posted by gokul

1st animation using blender

this is done by us just by viewing some basic tutorials yet to learn a lot...
so its not that great...ive posted it on youtube .
here goes :



Regards

Gokul
Karan
Priyam