In order to add textures to your objects, you must first have a material assigned to it. For the purpose of this tutorial, delete the default cube, add a UV Sphere, Set Smooth shading and pick "Material" from the material list (Figure 1).
Figure 1: Materials panel
To access the texturing section, click on the square checkerboard icon, third from the right. As you do this, pay attention to the breadcrumbs and notice it remembers what material you had selected before. The default texture name is "Tex" (Figure 2). Also notice that the texturing panel has the same basic structure as the materials panel.
Figure 2: Texturing panel
The top of this panel has texture slots, but they work a little differently than the material slots. These slots will stack up, depending on how many textures you have, but they will all be linked to the material from the breadcrumb hierarchy. You can also see this in the Outliner.
The texture slot at the top of the list can actually be thought of the bottom texture, or the texture that is applied first to the material. The textures stack up as you add them downwards.
Just like in the materials panel, if you click on the icon to the left of the texture name field, the texture list is revealed. Also, the "+" and "X" work the same way.
Click on the drop-down menu under the texture name field to bring up choices for the texture type (Figure 3).
Figure 3: Texture Type menu
Examine the list and the options. "Image" will be a common choice for your texturing needs. For this tutorial though, choose "Clouds" from this menu. Then, change the name of the texture to "clouds" in the name field (Figure 4). Under the Clouds section, you have options to tweak the appearance of this texture.
Figure 4: Rename texture
Look at the Preview window to see what the texture looks like, then notice the three buttons below the preview: Texture, Material and Both. Select each of these to see what they do, then select Both (Figure 5). You may render your scene with F12, but for this tutorial you'll find the preview is extremely accurate, so I've chosen not to include render images.
Figure 5: Preview both the material and texture
The first thing you'll probably notice is the bright magenta color on your texture. This is the default Blender color for textures. More than likely, you'll want to change that, so find the Influence section of the textures panel, towards the bottom. Locate the color swatch, at the bottom-left of this panel. Click on it and change it to black. Also, notice the "Color" slider under the Diffuse area of the Influence section. If you were to decrease this slider, how much that color swatch affected the texture would be decreased, or less visible (Figure 6).
Figure 6: Texture Color Influence
The preview updates; the magenta color is now gone. Move down to the Mapping section and click on the Coordinates drop-down menu. This currently says "Generated" (Figure 7).
Leave it on Generated, but examine the other options available. In particular, notice "UV" as an option. This is what you'll select if you're working with UV textures.
Figure 7: Texture Mapping Coordinates
While still in the Mapping section, click on the drop-down menu next to "Projection" (Figure 8). Change this to Sphere.
Figure 8: Texture Mapping Projection
Texture Color Ramp
The Mapping section was probably expanded by default. Notice that the Colors section might have been closed up. If so, expand it and click on Ramp to see the same options as in the materials section. Toggle this off after you've looked it over (Figure 9).
Figure 9: Texture Color Ramp
We briefly looked at the Influence section earlier. Browse the options a little more closely to see what channels you can make your texture affect. The Color slider controls the color of the texture. LMB-drag on the value to decrease it some and look at the preview to see that the texture cloud color is less prominent. This is the section you will use to create specular maps, reflection maps, bump maps, displacement maps, etc. Simply toggle the channel on and adjust its value (Figure 10).
Figure 10: Texture Influence
Add New Texture vs. Add New Texture Slot
To see how textures stack on one another, we need to add another texture slot. Be sure to understand that if you click on the "+" sign next to the texture name, this will only duplicate the current texture in its current slot. Instead, select the next "nameless" checkerboard square in the slot section, and notice everything below disappears except the "New" button. Click "New" to add a new texture slot (Figure 11).
Figure 11: Add Texture Slot
Stacking Texture Slots
The new Texture slot is called "Texture" by default. Each texture going down the slot list is actually layered on top of the one before it in the list. Just like in the material slots, think of the top texture as the base texture. Change the texture type to Voroni this time (Figure 12).
Figure 12: Add Texture Slot Voroni
Change the texture color again to black. It's difficult to see since we decreased the clouds Color channel, but the clouds texture can be seen behind this Voroni texture, if you look in the gray areas of the preview (Figure 13).
Figure 13: Change Voroni texture color to black
Disable Texture Slots
If you disable the clouds texture by "unchecking it," you will see the Preview update to ensure you the clouds had some effect when it was checked on. Toggle it back on with the check mark. Use these check boxes to enable/disable textures from rendering.
Change Texture Slot Order
You may also re-order the texture slots with the up and down arrows to the right of the texture slots. With "clouds" selected, hit the down arrow to move it below "Texture" in the list (Figure 15). This will give you different results depending on your textures, but in our example, there's not much change in the Preview result. Switch the clouds back to the top of the list.
Figure 14: Switch Texture Slot Order
Texture Blend Types
Part of the reason our textures didn't change much when we re-ordered them is because of their Blend Type of "Mix." Find the Blend Type menu at the bottom of the Influence section. When you click on this menu, several blend types pop up. If you have used any image editing packages, such as Photoshop, these were probably known as blending modes. You'll just have to experiment to see which one does what. (Figure 15).
Figure 15: Texture Blend Types
Since "Mix" is the default (and the one we are using), here is how Mix works with our example. Since both of our textures are grayscale procedural textures, this will be easier to grasp. Mix will tell your texture to make all white ares of the procedural to adopt the color of the color swatch in the Influence section. All black areas of the procedural will become transparent and allow the material/texture beneath it (above it in the texture slot list) to show through. All areas of gray will be a combination of semi-transparency and texture color.
If you want to try this, first disable the Voroni texture by un-checking it. Then, go back to the materials panel and make the Diffuse a light color, such as yellow. Also, increase the Color channel back to 1 in the clouds Influence section. This will cause the clouds to be more visible, as they were before we tweaked the texture (Figure 16).
Figure 16: Yellow material with black clouds texture
Next, change the Color swatch in the clouds from black to blue. Look at the Preview to see that the clouds are now a blue color, on top of a yellow color. Hence, white areas of the clouds texture have become blue, while the black area of the clouds texture have become transparent to show the yellow material color beneath the texture. And, the gray areas of the clouds texture are causing a semi-transparent blue color to appear (Figure 17).
Figure 17: Yellow material with blue clouds texture
If you were to now toggle back on and select the Voroni texture ("Texture") slot, the stacking effect will become more obvious. It will currently have a black "web" look to it that is covering the blue and yellow color of the sphere (Figure 18).
Figure 18: Voroni black texture over blue clouds and yellow material
Change its texture color to something such as red, then look at the Preview, making sure the "Both" button is on, and that you have "Texture" selected in the texture slots. Everywhere there was white in the voroni texture, has now been replaced with red when you changed the color swatch to red. Everywhere the voroni texture was black has now become transparent, allowing the blue color of the clouds texture to show through, as well as allowing the yellow color of the material to show through. Everywhere the voroni texture was gray, allowed a semi-transparent red color to appear (Figure 19).
Figure 19: Voroni red texture over blue clouds and yellow material
If you want to create a Bump Map, look for the "Normal" channel, in the "Geometry" area of the Influence section. If you want your screen to match the below images, either undo all the color changes from the previous example, or change the texture colors back to black. Either way, with the Voroni "Texture" selected, toggle on "Normal" (Figure 20).
Figure 20: Texture Normal Influence: Bump Maps
Look at the Preview to see that the Voroni texture has now created a bump map effect on the sphere, as well as keeping the black texture color (or red color if you kept the previous example colors). The clouds texture is there, as well, but less noticeable (Figure 21).
Figure 21: Voroni texture with both color and bump mapping
Now, try disabling the Color channel of the Voroni "Texture" to see the Preview show that it is now only affecting the bump map. Any color you now see will be from the clouds texture, which should be more visible now that the voroni texture is showing none of it's Color channel (Figure 22).
Again, if you kept the colors from the previous example, the Preview would show the Voroni bump map on a yellow and blue sphere.
Figure 22: Voroni texture with bump mapping only
Since all the textures are linked into our material, we can now easily apply those textures, as a whole, to other objects. Simply select another object and select that same material, and all the textures will come along for the ride. Just keep in mind that the names of the textures and materials are linked to each other. This means that if you apply the material to another object and then you tweak one of the textures on that new object, it will change that same material everywhere it's applied (on the original object as well). You would be wise to first duplicate the material with the "+" and do the same to the texture you want to tweak. Simply changing the name of the material or texture on a new object won't do the trick; it will simply change the name of the material and texture anywhere the previous name existed. This will especially come into play when you begin duplicating objects.
You may also mix and match between procedural textures and UV textures within the same material. However, realize that the UV's are associated with the geometry of the object. Therefore, if you apply a material with a UV texture on it to another object that has different geometry, you may get strange results.