GLSL - PBR 着色器 - 漫反射 IBL 组件无法渲染

Question

I have put together a program partially based on learnopengl.com.

The part that fails is in the fragment shader of a PBR shader when calculating the ambient component using an irradianceMap. I have already verified the map is being sent to the shader correctly, as well as all the other maps.

When run without IBL the scene looks like this:

But when run with IBL it looks like this:

As you can see, the spheres with the PBR shader disappear.

The section which causes the problem is as follows:

vec3 kS = fresnelSchlick(max(dot(N, V), 0.0), F0);
vec3 kD = 1.0 - kS;
kD *= 1.0 - metallic;     
vec3 irradiance = texture(irradianceMap, N).rgb;
vec3 diffuse = irradiance * albedo;
vec3 ambient = kD * vec3(diffuse) * ao;

colour = ambient +Lo;

Specifically the problem lies with the irradiance variable, which when I perform normal operations on it, it works fine for example if I multiply it by 0.01 it will darken significantly, as expected. However when I add or multiply for example the albedo variable with the irradiance it fails, and nothing is output. I have tried 1000 different combinations and variables, and I simply cannot understand why it won't allow this variable to combine with others. I don't see why multiplying irradiance.r by albedo.r somehow produces nothing. Even if both were 0 the result would be black, not the spheres disappearing entirely.

This for example works:

vec3 irradiance = texture(irradianceMap, N).rgb;

colour = irradiance;

As well as this:

vec3 irradiance = texture(irradianceMap, N).rgb;

colour = irradiance*0.01;

But this fails:

vec3 irradiance = texture(irradianceMap, N).rgb;

colour = irradiance*albedo;

As well as this:

vec3 irradiance = texture(irradianceMap, N).rgb;

colour = vec3(irradiance.r,albedo.g,albedo.b);

Or any combination of the above you can dream of. All the other variables around it work and output correctly. It's only when operations are performed with that specific variable that things go wrong. I literally cannot fathom why not, and have found few answers online.

Answer 1

Most likely shader compilation is failing due to albedo being undefined, wrong type, etc. You have uniform vec3 albedo; or equivalent defined in the shader?

From the examples you've shown, it certainly looks to be a problem with albedo and not irradiance .

Answer 2

I solved this problem, you must add this code when you load texture:

shader.setInt("albedoMap", 0);
shader.setInt("normalMap", 1);
shader.setInt("metallicMap", 2);
shader.setInt("roughnessMap", 3);
shader.setInt("aoMap", 4);
shader.setInt("irradianceMap", 5);

Here is what i did before:

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, albedoMap);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, normalMap);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, metallicMap);
glActiveTexture(GL_TEXTURE3);
glBindTexture(GL_TEXTURE_2D, roughnessMap);
glActiveTexture(GL_TEXTURE4);
glBindTexture(GL_TEXTURE_2D, aoMap);
glActiveTexture(GL_TEXTURE5);
glBindTexture(GL_TEXTURE_CUBE_MAP, irradianceMap);

It's working fine, but in this section, you must use both.