Is there a smart way to apply a better transition between colours while maintaining one solid colour per face?

Question

I recently started using blender for a project. I have tried using a color ramp with a transition between the 4 colours, but the result is too smooth when applied:

Im aiming to achieve this kind of effect:

Is there a way, or is it the long winded way?

Answer 1

The following script reads the face position normalize it and assign it to the vertex color of this face ( new group named 'face_pos' will be created ) :

import bpy

obj = bpy.context.object
obj_data = obj.data
group_name = 'face_pos'
#check for existing group with the same name
if None == obj_data.vertex_colors.get(group_name): 
    obj_data.vertex_colors.new(name=group_name)
color_map =  obj_data.vertex_colors[group_name]

#collect dimension info
dim = obj.dimensions
min_x = -1*min([p.center[0] for p in obj_data.polygons])
min_y = -1*min([p.center[1] for p in obj_data.polygons])
min_z = -1*min([p.center[2] for p in obj_data.polygons])

for poly in obj_data.polygons:
    pos = poly.center
    color = ((pos[0]+min_x)/dim[0], (pos[1]+min_y)/dim[1], (pos[2]+min_z)/dim[2])
    for loop_ind in poly.loop_indices:
        color_map.data[loop_ind].color = color 

we wont apply this vertex color but instead we use it as a face position input in the material nodes using the Attribute node and the vertex color name , then we manipulate this information to create the desired effect

material node the result is color transition for faces not points :

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This solution maybe a bit complicated but it introduce a trick for accessing other properties in cycles(this is not like drivers since it updates per point not frame)

Answer 2

if you select all of the faces in Edit mode and then use Alt+e to access the Extrude options menu->Individual.

Press the Esc key to cancel the movement.

Next, press Ctrl + i to invert the selection

Press x to access the Delete menu and select 'Faces'.

Now you should be left with only the extruded faces and they should be all separate components.

OPTIONAL:Personally, I would bake these results to a UV map probably using the 'Lightmap Pack'setting.
This way, the individual faces can be re-joined after baking. This helps keep the Outliner clean. The 3D Viewport should also run much faster when many Objects are joined together into one.

Make sure that everything is selected and press p to access 'Separate->By Loose Parts'.

Now enter Object Mode and make sure that all the separate pieces are selected then use the shortcut Ctrl+Shift+Alt+c to access the 'Set Origin' Menu. Choose the option 'Origin To Center Of Mass' and now the model is ready.

The 'Node: Input -> Object Info -> Random' is key here. This is why the faces are all separate objects. Random greyscale values will be assigned to each separate model and this can be used to modulate the colors ramp so the color transition is a bit more scattered.

Here is a simple node setup that uses the random node to change the relative brightness of triangles.

This next node setup uses a second color ramp combined using the Linear Light Blend mode, many of the other blend modes give interesting effects as well. This setup also uses a noise texture to modulate how the main colors transition across the model.

Here's the .blend file http://www.pasteall.org/blend/35306

Answer 3

I think you might want to set up Color Ramp node like that:

In this case, color transition will be a lot more sharper. To control the sharpness you can drag the control points in and out or change the Interpolation type (it's better than using default Linear one in this case, because it provides still smooth but more visible transitions, imo).

If rendered, objects might look like that: