How to Use Basic Key Framing and IPO Curves in Blender

GreyBeard’s Blender Tutorial
Tutorial No. 5
Basic Key Framing and IPO Curves

Welcome to GreyBeard’s Blender Tutorials, this is my fifth tutorial and it is on Basic Key Framing and IPO Curves. It should give you the basic knowledge you need to get started with animation and blender. Now, what is a key frame? Well, a key frame takes a snap shot of an object or measures properties at a particular frame of an animation. Blender then interpolates the values of these properties automatically between the key frames. Blender has two categories of key frames. Key frames that deal with “Objects” that is what this tutorial will be primarily about and Vertex keys which is for mesh animation frames and so if you want to make your character blink or smile that will be the subject of our later tutorial. Both of the above key frame categories have absolute in relative key types. That will become clear during the tutorial.

Now, what is an IPO (Interpolation) Curve? An IPO curve is the representation of the key frames and the way that Blender interpolates between them in the form of a graph. Blender’s IPO curves are fully editable. Editing the graph changes the animation and editing the animation changes the graph, that is a two way street. Blender’s regular curve editing commands are used to edit IPO Curves so if you already know how to do that, you got a step up on some people.

Now, some tips and strategies for using key frames and IPO Curves. Remember that object typed key frames and IPO’s are relative to their parent and only if no parent exists to the world coordinates. This is an important point to remember and it is quite useful. Before you parent, make sure that you clear all transformations, location and rotations or you may get some unexpected results. This is generally good practice always.

And now onto the modeling part of the tutorial, here we have a basic Blender startup screen. I am going to hit CTRL+up arrow and it will put us into our full screen mode and I am going to front view and let us just edit our default cube into an object, so we can distinguish the different axis of the object. I am going to B back select the top vertices “s, x, 0, enter” zero that I hit was not the zero on the numeric keypad. It was the zero above the letters. Let us make the top point going to side view. Let us scale and hold down the CTRL key doing it different way and scale it to zero. W, remove doubles going to top view, hit seven key on the numeric keypad. Select dollar vertices press “a” twice and upscale in the x direction point five. Hold down the control key and you can get an exact point five value. Back into front view here, if you noticed the purple dot there that represents the center of our object. I want that to be in the middle of the base here, so we do select all our objects and press “b” for box, “SHIFT+s” brings up this menu and we want to do cursor to selection, should make sure your pivot point is in median point first, though it might not work. So SHIFT+s cursor to selection, you noticed our cursor moved there and we have to tab and object mode, we will go to the edit buttons and then we will zoom in there. And, you can see in the edit buttons under mesh, there is the center cursor button, press that and you can see our cursor is moved, our central objects moved to where the cursor was right on the base of our object.

I am going to use another key, key combination now which is SHIFT+c and that zooms out of our view so everything is visible and places the cursor at the origin. Since, our object is still selected, I am going to do SHIFT+s and we are going to do selection to cursor. Now, we have our new object. I am going to top view, scale out of it. Let us scale our object quite a bit bigger. There, make it easily visible and we do our key framing and I am going to do CTRL+a, apply size and rotation. And, we are set to start key framing.

So, now I am going to split my top window into two and we are going to display the IPO Curve editor. On one side we got our 3D view on the inter side and we are almost set to key frame our first little animation here. You will notice in the buttons header there is this area here, this tells you what frame you are on and you will notice in our window here I am going to make this larger. Here, and I am going to scale this down a bit, using the CTRL and middle mouse button to scale in both directions. I am just scaling it to the size, so that we can see the keys as I enter them. The green line here is what frame we are on, we are on frame one here. You can see the frame one here. And you will also notice the little one in the bracket here that also shows you, which frame you are on.

Now, the arrow keys and this are the arrow keys that--not the ones that are in the numeric keypad again, but the ones below the home and end and delete, insert buttons there. If you use the left and right arrow keys, you will notice the frame value changes and if you use the up and down keys you will notice that changes by a value of ten. So, let us move it to frame one. We will grab our object and place it in the location and with the cursor in the 3D window, press “I” and we are going to insert key and you all know there is a bunch of different types here, there is location, rotation, size, available, selects all the previous things that you may have already keyed, but for now we are just going to do locations, so I am going to insert a key for location and you will notice it inserted an x, or y or a zed location here.

Now, you will see the orange colored line, it is at plus ten, so our Y coordinate is plus ten. The reddish colored line is at minus ten. You can see our X values minus ten and the yellow line which is the height. We have not changed the height it is at zero. So now, I am going to make an error, the most common error that people make is I am going to move my object and then, I am going to frame 21 by hitting the up arrow key twice. And you will notice, as soon I change frames, its popped back to where we had it at the beginning. That is because the IPO window here, wherever our green line cut crosses this, this is where Blender is interpolating in between. Now since, we only have one point it has put out straight lines. So, the order that we do our operations here is important.

First, you set what key, what frame you want so we will go to frame 21. Hit the up arrow key twice then you move your object, you grab it and press "I" with the cursor in the 3D window. And, you will notice there X axis has gone from minus ten to plus ten. The other ones have remained the same, our Y value is the same and our height has not changed.

So, let us key frame some more, remember the order. First, go to the frame, then move your object and then “I” and insert a location. I am going to quickly key frame in our last two here. I am going to frame 61, grab my object, press “I” insert key. I am going to now go back to the beginning again, so we hit the up arrow twice. I am going to grab my object, press “I” and then location. And now, you can see we have inserted our keys.

Now, I am going to zoom in on this window and try to attempt to explain in this scary IPO window to you here. Now, the value of whatever you are key framing is on this side, it is on your Y axis of this graph. What frame you are on is always on the X axis. The dots here are the key frames that you entered and the curve fit in between is what blenders interpolated in between. By default it uses a bizarre curve to interpolate in between and we can change that as all, I will show you later.

Now let is take a look at the side buttons to see what we can form in the object, IPO Curves, key frame. These are absolute keys, this key in absolute locations, so the X coordinate here, the Y coordinate is going to be ten, the X coordinate is going to be minus ten, the Y coordinate is ten, the set coordinate is zero. These are relative coordinates and they are—well, I call them relative coordinates, I guess it stands for delta location axis. These are relative to the starting position of where you start, so if I move my block, it would be ten from where I started from and minus ten from where I started from. I will make this clear later, but for now we will just call them relative keys, so these are absolute locations, relative locations, absolute rotations, relative rotations, absolute size, relative size, you can switch layers, as well. You can key what layer and object on, this is handy. Sometime you can switch something to a layer that is not visible and make it look like it is disappearing and have it reappear when you want. Here is the time, in which you can control how fast time passes for an object that is a handy one. We will take a look at that. Now, if I CTRL middle mouse button and I started shifting the mouse button or just drag with the little mouse button. Actually, you do not have to hit a key. I can scroll this. You may see the whole thing at once on your screen. These colors here are not the material colors, they are the colors for the game engine, so I would not be covering those and these are for particles, I would not deal with those this time. Either that would be in a separate tutorial for particles.

Now, if an object is white, it is visible okay? Now, if I hold down the SHIFT key when I left click on the objects I can add or subtract the keys that are visible. And these buttons here select the curve. You will notice the vertex keys on that curve turned white. You can select different curves, this is handy because sometimes these curves are on top of each other and you may find them difficult to select by left clicking in the window, although that is not the case with us here, but these are handy. Again, if you hold down the SHIFT key, you can add and subtract from the location.

Note that an object also has to be, even though it is selected, if it is not visible, the editing commands would not work on it, so it has to be selected and visible for editing and copying commands and stuff like that to work on. So, it further explains this menu, this is the name of this curve and since we are using absolute values, just so that we do not get lost, I am going to call this absolute as a name. And, we will look at some of the other features as we go along.

So, now the first thing we are going to do is we are going to change the type of interpolation in between the curves, so I will select them all, I will just hold down the SHIFT key like that. You can also press the “a” like you can when you are editing to select all the curves and we are going to press the “t” key with cursoring this window and here is the different types of interpolation we can do. First, we will track constant and I will just turn on the X and you can see it, the means that the constant value till it hits the next key. Let us see what the effect of that is. I am just going to press ALT+a in this window, the animation runs. First, I will scrub this back to just using the left button, you can scrub your animation. I am going to press ALT+a, animates this window, pressing ALT+a with the cursor in this window animates it and you can see it bounces from key frame to key frame. And, if I press SHIFT+ALT+a with the cursor, not in this window, both will animate.

So, you can see that the constant value makes something hop from key to key. I use the constant value when I am making things switch later set of certain frame, it will switch to a different layer. Let us look at the linear type key, linear, and if I press SHIFT+ALT+a in this window again, you can see that it goes around very quickly. You will notice it does not slow down when it hits the corner, it instantaneously stops, going in that direction, starts going in that direction, instantaneously at that speed, it looks rather unnatural.

And, the last type was the zero curve, that was the default sort of type and let us do a SHIFT+ALT+a, there. One more time, just for fun, it looks sort of like a runner rounding the bases in baseball, except he is going the wrong way. Now, we can extend, say we wanted this to loop a bunch of times, we can extend these curves. We do not have to keep on key framing, key framing or copying, copying the key frames, there is extend modes and let us take a look at those. And now, I will zoom in to the window and we are going to curve, extend mode. I have them all selected and we are going to go here in the cyclic, which means it will keep on repeating. And, you can see that the pattern keeps on repeating course. Now, let us zoom up again and now, when I hit SHIFT+ALT+a with the button there our pattern will keep on repeating. I am also going to set this animation button up here, let us say 5000, so it will interfere with this.

Now, you will notice that when it was doing at this corner, they did not go smoothly around that corner. It was going on this because we have a kink in our curve there. So now, let us zoom in to this window and see how we can add at these curves, okay? Now, let us just have one visible, so that we can only worry about one at a time. When you hit the tab key, just like you are doing in the 3D window and our handles become available for our points. Now, the easiest way I find to use these handles is to change the type of handle, originally when you come, when you tab in, you will see that the handles are in the mode called the line, so if grab one handle you can see it remains in a straight line. If I select the middle one and I press “h” both handles become free.

So, now when I grab one, it does not remain in a straight line, although you can see there is kink forming. If I press “h” again and I select the middle one and press “h” again, it goes back to get there lines. So, you can switch between three in a line by pressing the “h” key. Make sure I got the middle one selected here, so I selected everything and I am going to press the “v” and when you press “v” one handle points to the previous vertex and the other handle points to the next vertex. When you grab one of these handles, it access before, so now I am going to switch to H now there in the freemode they are black and then H again and there in the align mode, there is one more, that is the called auto, so you press SHIFT+h and it automatically hits in the smoothest curve, it can.

So now, that we know how to grab our handles, you notice if we have the middle one grabbed, we can move our key around, if we move it pass another key, it flops, so it is in between those other two keys, kind of neat. We can insert keys by pressing--holding down the CTRL key and left clicking. You see and it creates a new key and if you grab that one and edit like all the other ones and I am going to erase that. You can also select the key and SHIFT+d, copy it, duplicate the key. Middle clicking makes it--keep the same value, which is sometimes the handy thing to have. We are going to erase that duplicate key.

Another way you can insert a key is if we use the arrows keys to position our green line, which shows what frame we are on, we are on about frame 31 now. If I press “I” I get these insert key vertices under the current frame and right where it crosses our line it will create a key frame for us. So, I am going to erase that one again. So now, let us take this kink out with some quick editing, I am just going to grab it, try to make is smooth looking. You can also stretch this. I am going to have this one. I am not going to get very fussy, tab and that sort of smooth. Let us do the same for the x here, tabbing, grab it. Try to make it kind of smooth looking, tab, not bad. So now, if we zoom up and let us go back to frame one and we do SHIFT+ALT+a with the cursor in this window. We should get a nice smooth end and we should go whooping nicely.

Now, you can also insert key frames by moving our object here and adding more, I am going to zoom in some here. Note if you have the cursor here and you hit home, that is a again, not the home on numeric keypad but the home above the arrow keys and we move our cursor to a position. I can then grab our object and insert a key frame, location and you can see that is added and it is added in your key frames. I am going to click on the tab in. One thing I should mention is if we have multiple curves selected and we tab in, you can edit them all at once and you will notice that the last one I entered is this selected now. I am just going to hit X to erase the select. Tab on the line and home. You can do our SHIFT+ALT+a again, go back to frame one.

So now, the next thing we are going to look is the difference between what I call absolute keys and relative keys. Now, the first thing I am going to do is we call this one absolute. Well, I could spell it would be called absolute. I am going to create new one and by default it calls it absolute one and then I am just going to call this one relative. I will go back to our absolute now, what I am going to show you is, if I duplicate this object, SHIFT+d, it has an absolute key and this one has an absolute key. If I press ALT+a now or SHIFT+ALT+a with the cursor in this window, you notice that the two objects popped right up on top of each other and I am going to grab one again.

Now, that is because these are absolute coordinates. So, if we use these coordinates, our patterning should--each one should from its own starting point follow that same pattern that we have key framed in. So, what we are going to do is I am going to change the key frame type for this one to relative. And now, how do we move by press “I” here there is no devalue that I can key frame in. So, what we are going to do is we are going to copy these ones to here and I will show you how to do that. I am just going to zoom in on that window. First we make sure that one is selected and this is copied to the top. Select where we are going copy it to, paste, select the next one, copy, up, paste. Select the next one, copy, paste. So now if we look at--you see we have pasted those and I am just going to select our first 3D again and I am going to erase those ones. Now, we have our new--we have the same key frame, so they are relative for this one.

So now, when I do ALT+a or SHIFT+ALT+a, you will notice that this one stays, follows the same pattern where we started. This one is still--I select this one, notice it is using the absolute curves here. So, if we move these two and I grab them and I do an ALT+a, this one will pop back to here to go, but this one will rotate in its new location, SHIFT+ALT+a. That is the difference between relative and absolute or what I call relative and absolute coordinate.

So now, I am going to switch this one to use the absolute coordinates again. So now when I do ALT+a it moves so. I guess I have to ALT+g, clear the location, ALT+o clear the origin and now, when I do SHIFT+ALT+ everything is back. If some of these things every pop out, that is the order that you should do to clearing in. First clear, do an ALT+g clear its location and ALT+o and then clear its origin. Now, I am going to grab this and I am even going to make another copy, SHIFT+d and this will give me an opportunity to show you some other buttons. What I am going to do is when I press ALT+a and I am just going to zoom in on this one. When I press ALT+a you notice they will pop up on top of each other again. Now, I only have one of these selected, the other two were still here. I am going to change the time off set for this one, for that it will go into our object buttons down here and I am going to zoom in, so I will explain them to you.

Now, this is the time offset for an object, if this is depressed that works on the parent, by default they are both depressed. I seldom have to change this. This offset makes it work on the particle. If I press this, it tells me what speed it is going at the frame that I am at, right? If I go up to frame three, frame is slightly different. We go back to frame one, it tells me the speed that I am going. There, so that is just the way that we can calculate our speed and this is where we enter our time offset. So let us see what happens if I enter a time offset at ten. Now, I zoom up here and now go into here. Now remember, only one of these were selected that was changed, now when I do ALT+a. you can see by adding a time offset at ten or selected one is logging behind by ten frames. It is changed.

Now, if I go back into those time offset buttons. And I change this to minus ten and go up and press ALT+a again. Well, zoom in, ALT+a, you can see now it leads the animation by ten frames. Now, I am going to clear that offset again and quickly, set it back to zero and I will show you the automatic time button. What will I do is I will grab this one and move it out of the way. Now, if I select all three of these and I zoom into here and we use the automatic time button, it defaults to 25 frames, let us change it to say 40 frames. What it does is it will take our three objects and from the first one to the last one it will spread them out over 40 frames. So, we should see three objects chasing each other, the first and the last object are offset by 40 frames. I hope that make sense. Now, we will do an ALT+a and we have three objects chasing each other and the total distance from that one to that one is for 40 frames top. So, that is a little excursion from our main topic here. So now, I have got my main cube here, so this one is cube two, notice the name is written in here ,as well so I am going to erase that one and this one is cube one and I am going to erase that one. Now, I am going to go into our time offset to zero, so it should recline. So now, we are set.

So now the next thing I am going to do is to show you the effect. If this object is parented to another object and so, if the cursor at our origin, I am going to add and empty. And I am going to parent our object to the empty. Now before I parent I am going to CTRL+a, apply my size and rotation and I am going to select my object first and then the thing that is going to be the parent CTRL+p, you make a parent. So now, these curves are relative to the parent and the parent’s axis not the world axis. This is a very important fact. So right now, since our parent is at the world origin and the axis are pointing the same way as the world axis. Our animation should look the same. If I change the origin, this is the origin of our object so it is the origin of the axis, you will notice that is our new origin. And we can even--if I go into side view, let us rotate our axis by 90 degrees, now when I zoom in and we do ALT+a you can see it uses the orientation of this axis not the world coordinates. I hope that is clear. It is one way that you can get to key frame easily and object rotating on its own axis rather than the world axis.

So now, we can also have this following its own key frames and for now just to be quick, I am going to have this object use the same key frame as its child, so it is going to seven, popped here and do the pattern because this has no parent. It is going to use the world coordinates. This is going to follow the same pattern but using the coordinate system relative to the empty and by zoom in and we even go to solid mode to be interesting and I will press ALT+a and you can see, this has to zoom a little more, ALT+a you can see the result of it. Seven, one and CTRL+up arrow.

Now I am going to change, I am going to select this object and I am going to have a new IPO Curves that will call it rot for rotation. I am going to delete all these curves from it. I am going to clear my rotation or my location and I am going to clear my origin, as well. So now, when I hit ALT+o, it is just following exactly and so now, I am going to add a rotation around the empty said axis by keying it in here, so I am going to press zed and key framing in here and say it is going to do four rotations around the zed axis going around that is 360, 720, 1440. So now, I am just going to add them numerically. And we are going to hit the end key and at frame 81, we want 1440.

Now, angles, rotation angles and time, we have to divide this value by ten if scaled it by ten. And, the reason I did that is because if we have other curves and we use such big numbers as 1440 and what not, the other curves would just seem like little lines, you would not see the differentiation, so they have scaled the Y value by ten. Notice that if I press the home key with the button there. It still says 1440 here, but the value when you press the end key is 110 for that, something to be aware of. I am going to tab out and I am going make the extend mode of this. I can just extrapolate it, so let us go to our curve menu, extend mode, extrapolation. I forgot to set this one, and that frame. One, our rotation is zero. So now, when I go in here I am going to turn off the things, you will it should rotate about the z axis, since that is the one that we added the curve line. Note that we can tilt the empty. Go out and then I will press zed here now. We can do ALT+a and we can see it tilts around it.

So now, let us see what else we can key frame. Let us select our object again and we are going to select materials. And here you can see all the different material properties we can set for our object and it is almost everything that is every button here has some--can be key framed here. Some of it you have to enter manually, it does not all show up in the little menu, but we are just going to key frame the color. So, I am going to make sure I am at frame one and I am going to make our cube pure red. If I tab in and out it should turn red. I am going to press the “I” key, press the “I” key here we get that-- we have before, so we press it in the material button. Press “I” and we will insert our RGB values and you will notice that our red is full red and our other values are zero. Full is one in this case and then press the end key.

So now, I am going to say go up to frame 41 and we will turn it yellow by increasing the G with our cursor here. I am going to press I RGB and now when I press the home key here you can see that green went from 0 to 1 and 41 frames. Now, we will go back to frame 81 and we will set it to pure red again. Here we go, press the “I” key RGB. And now, we should make this cyclic, does no matter about this, one are straight lines anyway but we should make this cyclic other wise it will just change colors the first time it goes around and not every time, so we will curve, extend mode, cyclic and we will tab in and I will grab those two and move down, scale one in a bit, grab game and tab. So now, we have a cyclic thing, we will take a quick look. ALT+a, red, yellow, orange, red, orange, yellow.

Now, I want to look at the time curve and I am going to use the time curve for the zed for our empty mounting. Because, I am going to zoom in on our windows here and we are going to click time. Time works, the rate the time passes is equal to the value of the slope of the line, so if I have something going from zero, zero to say frame 81 it would be say 81 and that is the best way of changing this now. I am going to make it linear. This slope here is now at a slope of one like the rise or 81 over the run of 81, 81 over 81 is one, so time should pass at the same rate it did before. I will tab in to give exact values here. Press end, 81, now you will notice that the time I peel is also as the rotation IPO’s by a factor 10, so we put in 8.1. Now, we select that one and zero, it is only the slope of the line that we are concerned about.

Actually I am going to set this to bezier and the extend mode to extrapolation for now. So now, this animation if I do go back to frame one, I will do SHIFT+a is the same speed as before. Now, if I grab this point, tab, and hold it down. Now our animation will only take 50 frames to go around ones. So, you can see it is going around faster and if I grab this again and hold down the key, make ALT+a, shit+ALT+a, it is almost the same speed we were going before. I am going to hit this exactly at 81 frames.

Now let us zoom in here and we are going to add another key, so I am just going to CTRL+left click and tab and you will notice now, time will be going faster at the beginning and then slower in the second half but it will finish at the same time as it did before. So faster in the beginning, slower in the second time, let us see what that looks like. Now, we do ALT+a, faster in the beginning and a little slow down, because we have not got a cyclic curve here. It continues slowly, now this gives us a chance to look at the last extrapolation. I we use extend mode, if we did cyclic, you notice you get these breaks and the first—this slope does not match with that slope so it is not going to look very good, it is going to go jump in speed at this corner. I will show you, and then it is going really slow and then suddenly going faster again. So, we are going to use the extend mode cyclic extrapolation. And now, when I tab in and zoom in and grab one of these handles and smooth it out a bit. I am going to make it more extreme to0, so you can see. Let us got to a positive curve here, so when we go and it is going to go fast, slow, fast, slow. Zoom in, go solid ALT+a, fast and now it is going to slow down, speed up and then slow down.

Now we can also--I move this down a bit again, grab and insert another key with a CTRL+left mouse button click and grab this. Now, we have a negative slope here so what happens when you will find it, grab this to make it moving. You got to find that at this point, we are going be very quickly here, time is going to be backwards for our object and then it is going to speed up again. Let us watch the effect here. ALT+a and time goes backwards and then forward again, so you can have lots of fun playing with the time IPO. It has some very useful effects on particle, as well to make the particles go backwards.

Now, I am just going to do one more key frame type. Select our object again and when I grab the camera and you hold, I am going to make the camera track this object so the first thing you do is you select the camera and you select the object then you press CTRL key and then says make track, which is one—the constraint. And now, if we just select the camera and I will grab the camera, you will notice that the camera always points our object. Now, let us go to camera view and see what it looks like. Now if I press ALT+a we can see that our object follows the camera.

Now when it is far away like this, maybe we want our camera to zoom in on our picture and we can do that when we have a camera selected and we go here, you will see that there is a camera IPO. So now, let us go to our edit buttons and I will zoom in. This is where we set our lens and this is the clip start and the clip in, these are the three that we can key frame. I am not going to deal with this, the clip starting in. I am just going to deal with the lens for now. So, we are at frame one and it looks kind of far away, so I am going to increase our lens value, that is not bad and then with the buttons or with the cursor on the camera button press “I” and insert a lens value. Now, I am going up ten, it is a little bit big there, so I am going to decrease our lens value a bit. Press “I” and another one. Press the home key and we should be able to see all our key frames. Now go ahead, few frames again. Our lens is really big, so we are going to shrink it-again and press the “I” key. I will press the home, so we can see where we are. Now ahead of few frames again, now that is pretty good we do not have to change anything. It is going backwards, it is going forwards. And, it is getting kind of small, so I am going to increase our lens value of game. And press the “I” key.

Now, when we get to the end here at frame 81 wan to go to 81, I want this lens to be the same as our first lens, so I am going to zoom in and I am just going to tab in and select the first one and I am going to duplicate it. If I click the little mouse button as I move it across, you will see at the same value and hold down the CTRL key and you notice I can get precisely on frame 81. So now, tab out and we want to make this one cyclic, as well. So curve, extend mode, cyclic and we have to do some adjustment here. Grab it, and now let us see what our camera view looks like and it should zoom in and zoom out as we go. Had a little bit of problems with it, but we can play with it another time, I think you got the idea.

Well, it is all I am going to show about key framing. I just wanted to give you a good grounding on it. Tab, zed and I want to select the empty. We can view all our--you can see our time, curve and our locations curves. I know this is a lot to absorb. You are probably had to watch this video a few times if it is new to you before you get it all. Just remember that these curves are relative to the parent. As you can see by the way this is rotating relative to its parent and the parent, the empty does not have a parent, so it uses the world coordinates, now where we can build hierarchies of IPO curves. Also remember, that when the order that you insert key frames using the window, you first advance the frame then you move your object and then you use the “I” key to insert your key.

Practice makes perfect, good luck and happy blendering.

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