How to view vertex' colors?

Question

I'm a beginner.

Is it possible (and if so, how) to select a single vertex and change its color? I tried the "Vertex paint" mode, but couldn't find a way to select a single vertex and view its color.

Thanks.

Edit:

What I'm trying to do is to encode data with the vertex color so that my game engine will be able to act on that vertex differently, while the actual in-game color of that vertex will be determined by the UV coords and texture I apply. I'm using FBX as binary format.

IMHO this is a very basic functionality which should be exposed from GUI, so if someone here can open a feature request, that would be great.

Answer 1

A single vertex can have multiple colors at the same time, because it can belong to multiple faces (with different colors). The vertex colors are stored per face loops and not in vertices themselves:

Vertex colors can be viewed in Vertex Paint mode. In this mode individual vertices can also be edited with brushes:

The drawing can be constrained to selected faces, but not selected vertices. Blender doesn't allow this from the UI like other software you mentioned (Max).

You can set the colors to individual face-loop vertices with python like this:

for ipoly in range(len(ob.data.polygons)):
    for ivertex in ob.data.polygons[ipoly].loop_indices:
        ob.data.vertex_colors["col"].data[ivertex].color = (R,G,B)

Here is a script that when run in Text editor will add panel to properties (N) so you can assign vertex colors to vertices in edit-mode:

The viewing of vertex colors is still best in vertex paint mode, having this in panel would clutter it.

Code:

import bpy
import bmesh

class VertexColEditPanel(bpy.types.Panel):
    bl_label = "Vertex Colors"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"

    @classmethod
    def poll(self, context):
        ob = context.active_object
        try:
            return ob and ob.type == 'MESH' and ob.mode == 'EDIT'
        except (AttributeError, KeyError, TypeError):
            return False

    def draw(self, context):
        layout = self.layout
        bm = bmesh.from_edit_mesh(context.active_object.data)
        if bm.select_mode != {'VERT'}:
            layout.label("Vertex select only", icon = 'INFO')
            return
        selected = [vert.index for vert in bm.verts if vert.select]
        if not selected:
            layout.label("Nothing selected", icon = 'INFO')
        else:
            layout.template_list("MESH_UL_uvmaps_vcols", "vcols", context.active_object.data, "vertex_colors", context.active_object.data.vertex_colors, "active_index", rows=1)
            row = layout.row(align=True)
            row.prop(context.scene, 'color_picker', text="")
            row.operator("vertex_col.apply")

class ApplyVertCol(bpy.types.Operator):
    bl_idname = "vertex_col.apply"
    bl_label = "Assign"
    bl_description = "Assign color to selected vertices for selected vertex color layer"

    def execute(self, context):
        me = context.active_object.data
        bm = bmesh.from_edit_mesh(me)
        selected = [vert.index for vert in bm.verts if vert.select]
        bpy.ops.object.mode_set(mode='EDIT', toggle=True)
        for face in me.polygons:
            for vert_idx, loop_idx in zip(face.vertices, face.loop_indices):
                if vert_idx in selected:
                    me.vertex_colors[me.vertex_colors.active_index].data[loop_idx].color = context.scene.color_picker
        bpy.ops.object.mode_set(mode='EDIT', toggle=True)
        return{'FINISHED'}

bpy.utils.register_module(__name__)
bpy.types.Scene.color_picker = bpy.props.FloatVectorProperty(subtype='COLOR_GAMMA', default=(1,1,1), min=0.0, max=1.0, description="Color Picker")

Answer 2

The Blender UI does not offer a way to view/set the color of an individual vertex. Normally, you set the color of a face as the vertex has no width.

If you want a vertex to show a specific (visible) color, then you can align a cylinder on the vertex (with very small radius) and paint that cylinder.

You can access the vertex details from the Python console.