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KryptonianKid
01-27-2017, 07:22 AM
I'm using fracture and bullet in lightwave. I want to create ground debris shooting up from a collusion object from below.
What I'm struggling with is texturing the debris and making it land on a ground plane, I have no problem with a ground plane appearing invisible to the camera... but want the debris object to fly up and land on the plane that is on the same level as the fractured object starts from, with shadows still showing once the pieces land on the plane. The final effect will be applied to a video shot of me taking off from the ground.

MonroePoteet
01-27-2017, 11:43 AM
It's unclear to me what you want: debris that is originally laying on the ground (like paper, cans, sticks, etc.) to explode upward as if from a downward-pointing "exhaust" from the take-off, or the actual ground surface exploding as if something / someone is coming up through the ground or as if the "exhast" is so strong to actually break up the ground surface and leave a crater. From saying you're using Fracture, I'd guess the second case, but I'm not sure. Can you clarify?


mTp

bazsa73
01-27-2017, 02:47 PM
Hi Krypto, please upload a sketch or a screenshot because it is difficult to see what you exactly want.

KryptonianKid
01-27-2017, 06:25 PM
It's unclear to me what you want: debris that is originally laying on the ground (like paper, cans, sticks, etc.) to explode upward as if from a downward-pointing "exhaust" from the take-off, or the actual ground surface exploding as if something / someone is coming up through the ground or as if the "exhast" is so strong to actually break up the ground surface and leave a crater. From saying you're using Fracture, I'd guess the second case, but I'm not sure. Can you clarify?


mTp

Sorry I guess I wasn't clear in my description, my apologies...
Basically as the person takes off in the film there is a blast of debris from the ground breaks up which then flies up into the air and then settles back down... but want the debris to come back down and fall on the invisible plane ground... whilst keeping the shadows and texturing the debris.

djwaterman
01-28-2017, 12:00 AM
So the person is standing on the ground, and takes off, like Superman, is that it?

KryptonianKid
01-28-2017, 03:40 AM
So the person is standing on the ground, and takes off, like Superman, is that it?

Yes :)
I have already the effect setup in after effects with the takeoff, just need to work out how to have the ground break up and explode with the sudden take off.
Similar to in this promo from Supergirl... https://www.youtube.com/watch?v=wRopTZeB94s

pinkmouse
01-28-2017, 08:16 AM
Something like the title sequence to my tutorials? For that, there is no ground plane as such, just geometry.

For this, I'd create a block as big as required for the shot, and about 5-10cm thick. Several steps of fracture and wielding to get the required debris size in the required location, surrounded by a solid block. Copy fracture parts to a few other layers and play with different masses to get some variation, then animate with a suitable collider object or force. Add dust/smoke/particles to taste.

Probably about 2-3 days work in LW...:)

MonroePoteet
01-28-2017, 09:55 AM
Yes, as pinkmouse says, create a multi-layer object with an unfractured block, a block with the crater in it, the debris (Fractured), and a surrounding "ground plane" block. Rough sample scene attached.

The modeling was done by creating the center, high-res block (40x40 segments), creating a tesselated sphere with jitter to form the crater, copying the block into another layer and using Boolean Subtract (tesselated sphere in the background) to form the crater, and then with the other block layer in the background and the sphere in the foreground, use Boolean Intersect to form the un-fractured debris object. Triple the debris object, use Fracture to create the number of pieces (I used 300). Then, create the "Ground Plane" block surrounding the hi-res block as large as the debris pieces will explode outward.

In Layout, apply Bullet->Static Body to everything except the fractured debris object and the Bullet_WithCollisionCone (which is Hidden and deactivated in Scene Editor, as is the unfractured debris object). The Bullet_WithCollisionCone is a Kinematic Body with collision distance of 40mm, and the debris object is a Parts Body using Convex Pieces on it with Activation set to Start Sleeping.

The Block_WithoutCrater layer is dissolved to 100% across frames 13-14 to have the crater appear, and the debris object is dissolved to 0% across those same frames to make it appear as the Bullet starts hitting it and activating bullet calculations.

On the texturing, I just used the Grunge preset for the "Ground", and the Lava_2 preset for the Interior (created by Fracture) and the Crater just as examples. Presets are available by pressing F8 while in the Surface Editor and using the pull-down menu to select the class of presets. Both Grunge and Lava_2 are in the Rock preset shelf. All surfaces are double-sided.

Hope it helps! As I said, a rough sample scene, but should be the basic setup.

mTp

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prometheus
01-28-2017, 10:33 AM
He.. supergirl :)
I wasnīt aware of that show airing, effects look a lot better or a bit more expensive Than in the smallville series, though I am not sure about the actor playing supergirl, she doesnīt seem to fit the costume so to speak, neither in looks or in acting....even though she is pretty :)
the costume looks like adapted from the latest man of steel in terms of color and texture, though the s emblem looks horrible with yellow stripe inside of it...but enough off that off topics.

As far as the effect, yeah...something like what has been mentioned already, though I think what makes the effect looks cool...isnīt just a collision effect and debri flying apart, itīs the initial shockwave followed by the force thud impact that breaks down from center and out..and immediatly fractured piece start to levitate..not explode, not until she has taken off the pieces falls back, so itīs kind of a momentum where her power of defying gravity is actually shown in those fractured pieces levitating.

which means a similar effect should have fractured pieces just really start to be affected by gravity, we do not have such gravity per object control or part control, you could however weigth certain fractured parts, and release the weight on them so they may rise up a bit.

KryptonianKid
01-28-2017, 05:05 PM
Yes, as pinkmouse says, create a multi-layer object with an unfractured block, a block with the crater in it, the debris (Fractured), and a surrounding "ground plane" block. Rough sample scene attached.

The modeling was done by creating the center, high-res block (40x40 segments), creating a tesselated sphere with jitter to form the crater, copying the block into another layer and using Boolean Subtract (tesselated sphere in the background) to form the crater, and then with the other block layer in the background and the sphere in the foreground, use Boolean Intersect to form the un-fractured debris object. Triple the debris object, use Fracture to create the number of pieces (I used 300). Then, create the "Ground Plane" block surrounding the hi-res block as large as the debris pieces will explode outward.

In Layout, apply Bullet->Static Body to everything except the fractured debris object and the Bullet_WithCollisionCone (which is Hidden and deactivated in Scene Editor, as is the unfractured debris object). The Bullet_WithCollisionCone is a Kinematic Body with collision distance of 40mm, and the debris object is a Parts Body using Convex Pieces on it with Activation set to Start Sleeping.

The Block_WithoutCrater layer is dissolved to 100% across frames 13-14 to have the crater appear, and the debris object is dissolved to 0% across those same frames to make it appear as the Bullet starts hitting it and activating bullet calculations.

On the texturing, I just used the Grunge preset for the "Ground", and the Lava_2 preset for the Interior (created by Fracture) and the Crater just as examples. Presets are available by pressing F8 while in the Surface Editor and using the pull-down menu to select the class of presets. Both Grunge and Lava_2 are in the Rock preset shelf. All surfaces are double-sided.

Hope it helps! As I said, a rough sample scene, but should be the basic setup.

mTp

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Thanks MonroePoteet and the rest of you guys... I'll have a play around with it :)

MonroePoteet
01-28-2017, 05:35 PM
Here's another sample scene with the shockwave, a very short initial breakup (frames 30-38), and the "bullet time" effect (i.e. stalling out the explosion while the camera moves around). The modeling technique was the same, except instead of using a jittered tesselated sphere, I used the LW logo from the old LW content using the same Boolean ops to get the crater and the fractured logo.

The "shockwave" is just a disc with a hole in the middle, with a Gradient on both the Transparency and Refraction Index to make it distort the underlying geometry as it passes, scaling it up quickly to expand the range.

This probably isn't the right way to implement the "bullet time". What I did was put an envelope on the Bullet simulation's Gravity (in the World tab, ranging it down to 0.0 from -9.8 m/s and back up to get the pieces to drop), and also put an envelope on the Parts Body's Linear and Angular damping to stop them moving and rotating. I think NevronMotion is the better approach, or "baking" the Bullet simulation and playing it back with differing speeds, but I haven't used either of those approaches.

As well, there's a ZIPed MPG video of the render.

Good luck!

mTp

KryptonianKid
01-29-2017, 03:46 PM
Yes, as pinkmouse says, create a multi-layer object with an unfractured block, a block with the crater in it, the debris (Fractured), and a surrounding "ground plane" block. Rough sample scene attached.

The modeling was done by creating the center, high-res block (40x40 segments), creating a tesselated sphere with jitter to form the crater, copying the block into another layer and using Boolean Subtract (tesselated sphere in the background) to form the crater, and then with the other block layer in the background and the sphere in the foreground, use Boolean Intersect to form the un-fractured debris object. Triple the debris object, use Fracture to create the number of pieces (I used 300). Then, create the "Ground Plane" block surrounding the hi-res block as large as the debris pieces will explode outward.

In Layout, apply Bullet->Static Body to everything except the fractured debris object and the Bullet_WithCollisionCone (which is Hidden and deactivated in Scene Editor, as is the unfractured debris object). The Bullet_WithCollisionCone is a Kinematic Body with collision distance of 40mm, and the debris object is a Parts Body using Convex Pieces on it with Activation set to Start Sleeping.

The Block_WithoutCrater layer is dissolved to 100% across frames 13-14 to have the crater appear, and the debris object is dissolved to 0% across those same frames to make it appear as the Bullet starts hitting it and activating bullet calculations.

On the texturing, I just used the Grunge preset for the "Ground", and the Lava_2 preset for the Interior (created by Fracture) and the Crater just as examples. Presets are available by pressing F8 while in the Surface Editor and using the pull-down menu to select the class of presets. Both Grunge and Lava_2 are in the Rock preset shelf. All surfaces are double-sided.

Hey I've created the ground block doing 40x40 segments, then created the tesselated sphere with jitter and gone through to the Boolean Subtract (tesselated sphere in the background) when I do that, it creates the rough crater, but when it comes to doing the Boolean Intersect to form the un-fractured debris object. I get error Unable to generate contour... screenshot attached!

I have noticed when I do the Boolean Subtract, the jitter sphere crater lines don't match with the jitter sphere object... which I think is causing the error... Could it be I need more segments on the box itself?

Regards

Aaron

KryptonianKid
01-29-2017, 04:42 PM
Managed to fix the problem by using the intersect on another block.... to create the fracture piece...

KryptonianKid
01-30-2017, 04:43 PM
Here's another sample scene with the shockwave, a very short initial breakup (frames 30-38), and the "bullet time" effect (i.e. stalling out the explosion while the camera moves around). The modeling technique was the same, except instead of using a jittered tesselated sphere, I used the LW logo from the old LW content using the same Boolean ops to get the crater and the fractured logo.

The "shockwave" is just a disc with a hole in the middle, with a Gradient on both the Transparency and Refraction Index to make it distort the underlying geometry as it passes, scaling it up quickly to expand the range.

This probably isn't the right way to implement the "bullet time". What I did was put an envelope on the Bullet simulation's Gravity (in the World tab, ranging it down to 0.0 from -9.8 m/s and back up to get the pieces to drop), and also put an envelope on the Parts Body's Linear and Angular damping to stop them moving and rotating. I think NevronMotion is the better approach, or "baking" the Bullet simulation and playing it back with differing speeds, but I haven't used either of those approaches.

As well, there's a ZIPed MPG video of the render.

Good luck!

mTp

MonroePoteet I have followed your instructions and go to playing the animation... i'm running into two problems though, the first is when the collision object impacts on the fracture debris. The debris shoots up, but acts like it's in very low gravity with very light weight and shoots up but comes down incredibly slowly... I have gone into the world settings and set gravity to -9.8 but no change... It's probably something simple I've overlooked.

The second issue is when the debris goes up, for some strange reason I end up with a white cover over where the pothole should remain. :(

I've attached a screenshot of the scene animation showing what I mean with the white cover over the pothole...

And also attached a zip of the scene and object files...

Regards

Aaron

Thomas Leitner
01-31-2017, 04:04 AM
.... The debris shoots up, but acts like it's in very low gravity with very light weight and shoots up but comes down incredibly slowly... I have gone into the world settings and set gravity to -9.8 but no change... It's probably something simple I've overlooked....

Hi Aaron,
your object is very big (your ground is in Modeler about 70 m and scaled in Layout almost 13 times = 910 m). If you scale down your scene the simulation becomes much faster. Also bullet donīt like very big and very small scenes ( If I remember right, 10 m is a good value). If you parent everything to a null and scale this to something like 0,01 it works much faster (maybe you have to change [slow down] the animation of your collison object).


....The second issue is when the debris goes up, for some strange reason I end up with a white cover over where the pothole should remain. :(

Your FRACTURE:Layer4 object (Debris) leaves some polygons (with the "Rock" surface) behind. For bullet all parts have to be closed objects. You have to go some steps back: merge all points of FRACTURE:Layer3 object before fracture it again.

Hope it helps.
ciao
Thomas

MonroePoteet
01-31-2017, 12:38 PM
I think Thomas called out the primary issues: the Parts object (and everything else) is very large, giving it a MASSIVE density, so it moves really slowly. You also have the Dynamics Framerate set to 1000, which is going to make the simulation very slow. Another thing that it appears you did is have a NULL with no geometry as the Kinetic object (called BULLET), which means it impacts very little force to the Parts object.

So, I'd recommend: reduce the scaling down to 1.0 on all objects, fix the Parts object (you have a un-fractured copy in Layer 3, just merge points and re-do the Fracture), and cut down the Framerate to 180, bumping it up a bit if you start seeing collision-detection failures. I'd also eliminate your "BULLET" object and use the un-fractured Layer 3 as the Collision (Kinetic) object, setting it to "Hidden" and "Inactive" in Scene Editor (the first two columns).

You can also reduce the Linear and Angular Damping on the Parts object to get it to react more to the collision. Don't make it TOO small, it's already at 1.0%, so maybe reduce them to 0.5%

mTp

P.S. Forgot to mention reducing the Mass of the Parts object. The calculated mass is IMMENSE. Set it to "Given Mass" and maybe 100kg or so.

MonroePoteet
01-31-2017, 12:51 PM
Here's a modified Scene file with the proposed changes. On the Objects, I fixed the Fractured one as described, and then centered the Objects so the impact point is about (0,0,0), gave each layer names and parented everything to the GroundWithCrater layer (these last three changes are not required, I just prefer it that way).

Seems to work pretty well. You can change the amount of impact by just changing the initial Y position on Frame 0 of the Collision object. I also set the Y Envelope to be Tension = -1 and Bias = -1 so it accellerates both toward and away from frame 20, "thumping" the Parts object good and hard.

mTp

P.S. Although I "fixed" the scene and objects, I'd recommend you do it yourself for practice. The more you mess with the Bullet parameters, etc., the easier it'll get to do new scenes.