Grayscale bump map in Panda3d?

Scripting Issues
1

Hi!
Is it possible to use grayscale (black/white) bump map instead of normal map?

2

Hi, welcome to the community!

No, afraid not. You need a tangent-space normal map for bump mapping. A grayscale bump map can only be used for parallax mapping. You will need to convert it. I believe there are tools for this.

3

You could perhaps write a shader that makes use of a bump-map–but I doubt that it would be as effective as a normal map, and might be less efficient.

(Converting your bump-map to a normal-map, as suggested by rdb, is likely the better option. I believe that GIMP can do this, for one.)

4

You certainly could write such a shader; you would need to sample the neighbouring texels of the bump map and calculate the normals based on the difference in height. This would be quite a bit less efficient and put more strain on the texturing pipeline.

1 Like
5

Yes, something like this, copied from stackoverflow.

    const vec2 size = vec2(2.0,0.0);
    const ivec3 off = ivec3(-1,0,1);
	
    vec4 wave = texture(p3d_Texture0, texcoord);
    float s11 = wave.x;
    float s01 = textureOffset(p3d_Texture0, texcoord, off.xy).x;
    float s21 = textureOffset(p3d_Texture0, texcoord, off.zy).x;
    float s10 = textureOffset(p3d_Texture0, texcoord, off.yx).x;
    float s12 = textureOffset(p3d_Texture0, texcoord, off.yz).x;
    vec3 va = normalize(vec3(size.xy,s21-s01));
    vec3 vb = normalize(vec3(size.yx,s12-s10));
    vec4 bump = vec4( cross(va,vb), s11 );