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I'm trying to make my plane (ground) explode up into the air. However i only want a small section of it to explode (as if an object is shoot out of the ground). I'm new to blender so i not to familiar to the interface and I'm using version 2.77

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  • $\begingroup$ So like the result of this youtu.be/2R7N8UqT04U ? $\endgroup$
    – cturtle
    Aug 8, 2016 at 1:14
  • $\begingroup$ A little more condensed, like this? imgur.com/a/p2VAC $\endgroup$
    – metaphor_set
    Aug 8, 2016 at 2:21
  • $\begingroup$ metaphor_set yes like that.. is there a tutorial? $\endgroup$
    – mlm
    Aug 8, 2016 at 17:43
  • $\begingroup$ I can make one, it might take a day until I have time... $\endgroup$
    – metaphor_set
    Aug 9, 2016 at 3:03

2 Answers 2

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Introduction

The discribed method is only one of several methods to create an animation of a ground explosion and it's the fastest method that I know. It will cover only the basics of preparing the plane, creating the debris and setting up the physics to get this result.

enter image description here


I won't go over the task of texturing here, since BlenderSE is not the best medium to create long tutorials. A good method to texture the debris is described in one of the Timster's videos which you can find here: Project Assets: Low Poly Rubble

Blend file:

Prerequisites

In order to get nice debris, we are going to use the Cell Fracture addon. Hit Ctrl+Alt+U to show the User Preferences, to to the Addon Panel and type "cell" into the search field. On the right side, activate "Object: Cell Fracture", (if you plan to use the addon regularly, you also might hit "Save User Settings"). Close User Preferences.

activating cell fracture addon

Preparation of the Base Meshes

Add a plane, resize it to a reasonable size and subdivide it (If you already have a plane or a terrain of some sort, you can use that as well, as long as it has not too many faces). Move your vertices around in the area where the explosion should take place, until you have a nice uneven jagged area. To get a nice shape you might enable proportional editing mode for the rough shape and disable it again for the finer details.

base mesh


Select the faces for the hole, then press Numpad 1 to go to front view, then press E and Z extrude the vertices down on the z-axis.

extruding hole


Enable Face Select, turn off "Limit selection to visible" and select all the faces below the ground plane. Hit Shift+D to duplicate them, then hit P and select "Selection" to create a new object out of the duplicated mesh. Tab into Object Mode, hit M and 2 to move the new object to Layer 2.

Creating the debris - step 1


You should now have two objects like these below, each on its own layer.

ground mesh and debris mesh

Rename the object on Layer 1 into "ground" and the object on Layer 2 into "debris".

renaming the meshes


Go to Layer 2 and tab into Edit Mode. In front view (Numpad 1), enable "select vertices", "Snap during transform", set "Type of Element to snap to" to vertex and also enable "Automatically merge Vertices". Select all vertices of the ground plane. Hit G and Z to move them up on the z-axis until it snaps and fuses with the original mesh.

Creating the debris - step 2


Still in Edit mode, hit A until everything is selected, then hit Ctrl+N to make the normals of your mesh face outwards. Select the vertices of the ground plane again and move them on the z-axis until the height of your mesh is about 3/4 of its original size. Then scale the ground plane down to 0.9 (Hit S then 0.9).

Creating the debis - step 3


Hit Ctrl+R to add two loopcuts (Mouse Wheel up), then tab into object mode.

Creating the debis - step 4


Add a Subdivision Surface modifier, set its type to "Simple" and the Numbers to 3 and click "Apply". Then go to the Tool Panel (T), go to "Tools" panel and click the Cell Fracture Button (it should have been added by the Cell Fracture addon, see Prerequisites). In the now opened Settings Window, set "Source Limit" to 250, select "Random" and click OK.

subdiv modifier and cell fracturing


You should then see something similar to to this in the 3D viewport.

cell fracturing process


You now still have your original debris mesh in Layer 2 and the newly generated fragments in Layer 3. Switch to Layer 3, then go to the Outliner and select the mesh that should be called "debris_cell". This is now your active mesh. Move your mouse pointer to the 3D view and hit A to select all objects.

all selected, one active


Physics

Go to the Tool Panel, then to "Physics" and click on "Add Active" (note how the outline of your selected objects turn from yellow to green in the 3D Viewport). Then go to the Properties Window, switch to the Physics Panel, go to "Rigid Body Collision", enable "Collision Margin" and change it to 0.15 (this influences the force). Go back to Tool Panel - Physics and click "Copy from Active" to apply the changes to all the selected objects. Reminder: You'll have to do this every time, when you change something in the Physics Panel!

prepare debris physics


Play Animation

Go to Layer 1, select your ground mesh, then go to the Tool Panel - Physics and click on "Add Passive". The ground mesh now should also have a green outline. Go back to Layer 3, hit A until everything is selected, then M and 1 so move everything to Layer 1. Hit A until nothing is selected go to the timeline area and hit the "Play Animation" button.

move debris and play animation


Enjoy!

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  • $\begingroup$ Well formatted and great annotations on the images. :) Do I understand it correctly that you simply used the force caused by the debris being close to each other (collision margin and penetration penalty) for the dinamics? $\endgroup$
    – Róbert László Páli
    Aug 10, 2016 at 8:40
  • $\begingroup$ @Róbert László Páli Thanks. Yes, the force caused by the collision margin should be enough for a simple scenario. $\endgroup$
    – metaphor_set
    Aug 10, 2016 at 8:44
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I have a procedure that produces a result like the following. If you wanted it to explode differently, I would recommend using Force Fields.

enter image description here

  1. Shift + A > Mesh > Plane.
  2. Key S and drag to scale up the plane.
  3. Tab into Edit Mode.
  4. Key W to open the Specials menu and select Subdivide.
  5. Key T to toggle open/close the Toolshelf.
  6. Change the Number of Cuts to 10.

       enter image description here

  1. Key Shift + R to repeat the previous operation.
  2. Deselect everything that you want to explode.
  3. Go to the Properties panel > Object Data tab and add a new Vertex Group. Name it Explode. Make sure that the Weight: value is set to 1.
  4. Click Assign.

       enter image description here

  1. Tab out of Edit Mode.
  2. Key Space and type Quick Explode. Key Enter.
  3. Go to the Properties panel > Object Modifiers tab > Explode modifier and select the Explode vertex group.
  4. Click Refresh.

       enter image description here

  1. Go to the Properties panel > Scene tab > Gravity dropdown and change the Z: value to 10.

       enter image description here

  1. Go to the Properties panel > Particle Systems tab > Emission dropdown and change the End: value to 50.

       enter image description here

Here is the .blend file:

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  • $\begingroup$ @mlm If my answer helped, please consider marking it as accepted by selecting the check mark in its upper, left-hand corner. It would help me greatly and make me very happy! $\endgroup$
    – Shady Puck
    Aug 9, 2016 at 3:21

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