Changing Colors of a Moving Object

[Anonymous]

Hi All,

Here's an example of what I want to do. Suppose you have an object moving along the x-axis while the viewport is in perspective and the object has to change its color from blue to red at a certain point of time. In addition, say we want to have the word 'change' appear as a subtitle (flat on the screen, not in perspective) right at that same moment of time, stay on for a second and then disappear. Would appreciate it if someone can help. Thanks in advance.

[Steve_Curley]

Use a blend material - Red in one slot, blue in the other, animate the Mix Amount.

For the text - probably a bitmap (with an alpha channel) on a Plane object carefully positioned to be "in shot" at the right time, or "select and link" it to the camera. Animate the object's Visibility or the material Opacity to make it appear / disappear.
Or you could use a Text object instead of a plane with a bitmap.

Which version of Max are you using? (put this, and brief system specs, in your sig - saves us having to ask 😉 )

File is Max 9. Note that you won't see the colour change in the viewports, you'll need to render it.

11474_rc5UHJmRwmzt2oPhthxe.zip

[Anonymous]

Thanks a lot, Steve. Works great. What remains now is to learn how to do it. Also, can't find where to place a permanent sig. Here's what I use: 3D Max 2009 on 1.2 GHz SONY VAIO (Centrino Solo) w/ Windows XT SP2.

[Anonymous]

Probably I should’ve said exactly what I need this for. What I need to do is have an object, say a rod, moving at a certain speed and a ray of light starting at a certain moment from the one end of the rod. Eventually, having a higher speed, the light ray catches up with the other end of the rod and after reflection goes back to the first end of that rod.

The time when the lamp flashes (at the one end of the rod) to emit the light ray, as well as the time when the ray reaches the other end and is back to the beginning should be marked by texts stating the values of those times.

I’m managing to have the rod and the light ray have different speeds by making the beam cover a longer path than the rod and, since the background will be green, the ray will only be visible when switching to red and that’s gonna be the moment when the flash occurs. Maybe there are other, simpler ways of controlling the speeds of objects independently but I couldn’t figure them out yet.

[Steve_Curley]

The "how" is quite straightforward. A Blend material has 2 sub materials - open the Material Editor and click the sample slot. The Mix Amount is animated so that it is 0 up to frame 49 (shows just the 1st material) and 100 from frame 50 onwards (shows just the 2nd material). Drag the time slider and you'll see the number change at frame 50. The Text object is made visible in a similar way - select the text and open a Curve Editor - you'll see the keys.

Advice at this point would be to do the tutorials which come with max - they cover a lot of things which you'll need to know in order to use Max effectively. Help > Tutorials will get you started. Also learn to use the main Max Help - it covers pretty much everything in considerable detail.

To change your sig, go into your User Profile, on the left there's a list of options, Edit Signature is the 2nd one down under "Personal Settings".

[Anonymous]

This was really helpful. Thanks. I wonder if I would've understood it from the somewhat diffuse explanations in the tutorials. The gist is to understand that Blend is actually a type of material (a mixture of, really, two component materials, mixed in a given proportion). That I wouldn't have known just by reading from the tutorial, I guess.

Anyway, the color thing is done. What remains is the text. What I do is prepare a text object and hide it somewhere out of view. Then I pop it up at the right moment and move it away later. The greatest problem is to have it flat on the screen (and not in perspective) which I achieve by various rotations. That's cumbersome, though. Placing text is cumbersome, anyway -- as I've understood so far, the only way to type, say, text in black is by bevel which isn't as straightforward as one would expect. (As a matter of fact, I wouldn't for the life of me have known the 'bevel' way of making text from the tutorials, had there not been someone to mention it to me).

[Steve_Curley]

You found the Sig at least 🙂

Help, Help and more Help 😛
Anything you don't quite "get", look it up in the help. The tutorials are to get you started not to teach everything there is to know about Max. That's an (almost) impossible job, but the Help does describe what pretty much everything does. So, searching the help for "blend material" (it's about 4th in the returned list) will get you everything I said and then some.
Tip. The tutorials for Max 2009 are not (sadly) as comprehensive as those for earlier versions - you can (fortunately) still obtain the ones for Max 9 from here.

Easy way for the text. Create the text in one of the Orthographic viewports, front is probably easiest. Create a free camera and position it so that it is facing the text (use the ortho vewports for moving / rotating it). Select the perspective viewport and press "C" so you can see what the camera sees.
Make sure the rotation of the camera is lined up with the world axes - it will then be perfectly "flat on" to the text (which is automatically created flat on the X axis. Adjust the size of the text and move it so it's positioned appropriately. Make sure you don't rotate anything at this stage. Use the Select and Link (on the main toolbar) to link from the text to the camera. Now, whatever you do to the camera, move or rotate it, the text will always follow and should stay perfectly aligned. Note that changing the lens diameter WILL make the text appear to move in relation to what the camera sees so avoid that if possible.

Extrude, Bevel and Bevel Profile can all be used to give some shape and depth to your text, however I should warn you that because of the way the text is constructed you will find your polygon count and memory usage going through the roof if you're not careful. Read this thread carefully then decide whether you really need all that extra detail.
You could always do what I did and just apply a Edit Poly modifier - result is flat filled-in text which is less resource hungry than the other methods. Or you could just convert it to Editabale poly, but then you lose the ability to change the text, the size etc etc.

(again with the help, sorry) If you search for "text" in the help the Bevel modifier is in the list - a ways down, admittedly, but it is there. Knowing which modifier to use for a specific job is something which comes from experience rather than from tutorials (though they can help).

[Anonymous]

Thank you, Steve. You were very very helpful. Without your clear explanations it would've taken me quite a bit of time to get all this. As in most things there are some pivotal moments to be understood, usually hidden in a heap of words and distractions in those manuals and tutorials. How much easier it is to just explain and emphasize, as you did, that Blend is a kind of material and that a camera view can substitute everything else in terms of presentation of a scene. I should admit, though, that things turned out to be more complicated and require much more work than I initially expected. This is a different type of problem, concerning productivity and creativity, other than just staring at the screen having no clue where to begin. Thanks again and all the best.