How to change the active material of an object while game is running?

Game Engine Game Engine Support and Discussion
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1

Why can a mesh have more than one material slot. You are only able to have one active material on a face. What is the reason for having multiple material slots?

Is there a way so swap out the active material while a game is running. I found this code that will swap the material in slot 0 with the one is slot 1, but the texture of my object never changes.

a=bge.logic.getSceneList()[0].objects.get('Bedrock') #select object Cube

        print((a.meshes[0].materials )  ) #show its materials
        mat=a.meshes[0].materials[0]  #copy current material
        a.meshes[0].replaceMaterial(0, a.meshes[0].materials[1] )  #replace first material with the second (which has different color of curse :-)
        a.meshes[0].replaceMaterial(1, mat) #copy the 1st material to 2nd slot
        print((a.meshes[0].materials )  ) #show materials list

This will swap material 0 and material 1, but the texture will not change.

This code below will change the texture on the active material.

ID = texture.materialID(a, 'MABedrock')

    # create a texture object
        object_texture = texture.Texture(a, ID)

    # create a new source with an external image
        url = logic.expandPath("//Textures/bedrock.png")
        new_source = texture.ImageFFmpeg(url)

    # the texture has to be stored in a permanent Python object
        logic.texture = object_texture

    # update/replace the texture
        #logic.texture.source = new_source
        logic.texture.refresh(False)

How do I get the active material to change and have the texture of my object change to the one of the new active material?

2

i have made a test file for you that is working… i remember many years ago, when i made a commercial application with bge 2.49 or so — VideoTexture was pure pain :slight_smile: … because i had no idea

check out on github:

https://github.com/sevi78/UPBGE-Tests

look for VideoTextureTest

2 Likes
3

What version of the engine are you using? UPBGE 3.0 supports using bpy, which is how I do this.

4

sidequestion: i remember in the past (2.49 or so —), that bpy doesn’t work on runtimes. has this changed? would be great

5

Bpy works in game in 3x

But you need to use it.

import bge
cont =bge.logic.getCurrentController() 
own = cont.owner 
Mesh = own.blenderObject

Kx_meshProxy is replaced with blender mesh / or bmesh api.

6

0.3.0

The idea is that I will have 5+ blocks. They will all share the same model, but have different textures. So instead of creating 5+ models of the same cube and assigning a different materials, I was wondering if I could just create one block model and assign it the correct material when I spawn it into the world.

7

if you want them to exist at the same time, then you will need to have five different objects (afaik). But if they only exist one at a time, then the following should work:

a = bge.logic.getSceneList()[0].objects.get(‘Bedrock’)
a.blenderObject.active_material = bpy.data.materials[“myMaterialName”]

8

We can unwrap to the bottom of an atlas, and add object color to the uv, offsetting it. (in shader nodes)

This way everything is 1 material