Zmerge page 4

PAGE 4
There is a great difference between the real world and the world of virtual 3d. When two solid objects touch in real life, they stop moving. In the virtual world they keep moving and blend into each other, with bits of each other poking out. This is something you need to be aware of, because if you don't want them to behave like that you must use z-elevation values large enough to keep them apart. But on the other hand, it can be a very useful feature for building models.
We are going to take advantage of this ability of objects to melt together to build a very simple model - a mace - one of those spiky ball weapons.
We will begin by creating a simple 3d ball. Use the path tool, seen depressed in the picture on the left. Click on whatever shape is shown and choose the circle. Use a light colour for now. When we have seen how the pieces fit together we will change them to a metal. Select 3d round for the mode, and click and drag a circle in your image. You will get a sphere like the one on the right.
A 3d round path object sphere has a lot of virtual 3d depth of its own. It is not like the stamp images we used on the previous page, which were virtually flat. Nor is it like a 3d pipe object, which has a limited depth unless you use the virtual trackball. We shall be able to embed things in this sphere very easily.
Select the base image, either by clicking in the background of the image itself, or by clicking in the layer manager on the area just underneath the sphere thumbnail and its info panel.
Use the path tool again, but change the shape to an ellipse, and the colour to something that is a real contrast with your sphere. In the path panel (if it is not in your workspace click the panel button on the attribute toolbar), on the options tab, check draw from center and disable object pick mode while drawing. If you don't check the second one, the minute you put your cursor on the sphere it will be selected. By checking these options we can make sure that we draw an ellipse that sticks out of the sphere by the same amount both sides, but for the time being, if you want to select anything, you have to do it by clicking the object thumbnail in the layer panel. Keep even-odd fill and antialiasing checked too.
Put your cursor in the centre of the sphere and draw an ellipse. Keep it thin and spiky - remember that this is going to be a nasty weapon. Draw another vertical one. We now have two ellipses crossing in the middle, but we also need two angled ones between them, and you cannot draw angled ellipses. So select the one you just drew, and copy it to the clipboard. Paste a copy into your image, and drag it to exactly above the one you just drew.
Select the transform tool, and set the figure in the rotate box to 45 degrees.. Click the arrow at the left of the rotate box. Paste another copy of the ellipse into your image, drag that above the vertical one, use the transform tool rotate box, but this time click the arrow to the right. Your image now looks like this.
Go to the path panel and uncheck disable the pick mode, so you can once again click on objects to select them. Now the fun begins as we z-merge these objects.
Start by selecting the sphere, use the z-merge tool and check the z-merge box. Leave the sphere's z-elevation at 0. It will jump in front of the spikes. Select the horizontal spike and z-merge that. Then give it a z-elevation value that brings it forward so that it can be seen to be sticking out of the sphere. The exact figure will depend on the size of your objects. I used 40, but just keep increasing it 10 at a time, till it looks right.
Now do the same with the vertical one, but give it a higher value - I used 50 - because we do not want the spikes placed symmetrically. I gave my two angled ones z-elevation values of 54 and 63, and below left was how they looked.
Then change the materials. I gave the sphere steel 3 from the easy palette materials gallery metallic group, and the spikes steel 4. On the right above you see how that looked.
One last little touch is needed - a spike coming towards you in the middle. We have to do this after assigning the materials, because we are going to have to do transformations which would mean the material would not apply properly. So now, copy/paste the horizontal spike. Use the transform resize tool to shorten it - this one would look strange if it sticks out of the back.
Although this is a path object, you will find the virtual trackball greyed out, and you have to convert it to an image and back to a path object to bring the trackball into life. After that double conversion the materials do not apply properly, which is why we need to have the material we want in place before it is copy/pasted.
Rotate it with the virtual trackball till it is pointing upwards and slightly to the left of straight out of the picture. Place it in the centre of the sphere and change the z-elevation till it is poking out of the centre of the sphere. You may have to keep adjusting the rotation and the z-elevation value several times till it looks reasonably convincing.
And there it is - an object made from z-merged shapes intersecting with one another. If you select all the thumbnails from the layer manager, right click and use the menu group option, you will have an object that you can move around freely and use in your images.
I hope this tutorial has given you an insight into z-merge, and lots of ideas for your own z-merged objects. Have fun with z-merge!

©Carol Brooksbank (Carol UK) 2001
Please do not copy this tutorial to any other website. It may be downloaded for personal use, but it may not be distributed in any way, free or paid for.
You are most welcome to link to my Graphics website at
http://www.caroluk.co.uk/graphics/
where you will always find a link to the current URL for my tutorials.