Ambient Occlusion Map

[SpiderPig]

As per the workflow here I've create a AO_ROUGH_METAL map with AO in the red channel but it appears to not be showing up on the model when rendered.  Looking at the PBR/Fragment.glsl shader it looks like AO is only being loaded from it's own dedicated slot.  Is this intentional or can t be revised to use the red channel of the same texture that metal & roughness are in?

if (material.textureHandle[TEXTURE_AMBIENTOCCLUSION] != uvec2(0))
{
    float ao = texture(sampler2D(material.textureHandle[TEXTURE_AMBIENTOCCLUSION]), texcoords.xy).r;
    f_diffuse *= ao;

    // apply ambient occlusion to all lighting that is not punctual
    f_specular *=ao;
    f_sheen *= ao;
    f_clearcoat *= ao;
}

 

[SpiderPig]

To test it I did this.

ambient_occulsion is 1.0f by default.

#ifdef MATERIAL_METALLICROUGHNESS

    //--------------------------------------------------------------------------
    // Metallic roughness
    //--------------------------------------------------------------------------

    materialInfo.metallic = material.metalnessRoughness.r;
    materialInfo.perceptualRoughness = material.metalnessRoughness.g;
    
    if (material.textureHandle[TEXTURE_METALLICROUGHNESS] != uvec2(0))
    {
        // Roughness is stored in the 'g' channel, metallic is stored in the 'b' channel.
        // This layout intentionally reserves the 'r' channel for (optional) occlusion map data
        vec4 mrSample = texture(sampler2D(material.textureHandle[TEXTURE_METALLICROUGHNESS]), texcoords.xy);
	ambient_occlusion = mrSample.r;
        materialInfo.metallic *= mrSample.b;
        materialInfo.perceptualRoughness *= mrSample.g;
    }

    materialInfo.perceptualRoughness = clamp(materialInfo.perceptualRoughness, 0.0f, 1.0f);
    materialInfo.metallic = clamp(materialInfo.metallic, 0.0f, 1.0f);    

    // Achromatic f0 based on IOR.
    materialInfo.c_diff = mix(materialInfo.baseColor.rgb,  vec3(0.0f), materialInfo.metallic);
    materialInfo.f0 = mix(materialInfo.f0, materialInfo.baseColor.rgb, materialInfo.metallic);
#endif

I only use it if there is no AO map specified.

if (material.textureHandle[TEXTURE_AMBIENTOCCLUSION] != uvec2(0))
    {
        float ao = texture(sampler2D(material.textureHandle[TEXTURE_AMBIENTOCCLUSION]), texcoords.xy).r;
        f_diffuse *= ao;

        // apply ambient occlusion to all lighting that is not punctual
        f_specular *=ao;
        f_sheen *= ao;
        f_clearcoat *= ao;
    }
	else{
	f_diffuse *= ambient_occlusion;
	f_specular *= ambient_occlusion;
        f_sheen *= ambient_occlusion;
        f_clearcoat *= ambient_occlusion;
	}

 

[Josh]

AO will only be rendered when the AO map is assigned to the AO texture channel...BUT...

The AO map and the metal-roughness map can be the same texture. So if you assign it in both slots, you have AO.

This is the way glTF does it. I don't think it really requires an extra texture sample in the fragment shader, because of the texture cache.

[SpiderPig]

Oh I see, so just give the texture to both slots.  Yeah like you said, the only thing I don't like about that is the extra texture sample as TEXTURE_METALLICROUGHNESS already has the AO sampled in mrSample.r.