Review PBR shaders

Issue was related to vertex tangent attibutes not uploaded to GPU, a quick solution was implemented for new vertex attributes loading for already existing meshes... I don't like it specially but it will work for now.

examples/models/resources/shaders/brdf.fs

@@ -10,13 +10,13 @@
 
 #version 330
 
-#define         MAX_SAMPLES        1024u
 
 // Input vertex attributes (from vertex shader)
 in vec2 fragTexCoord;
 
 // Constant values
 const float PI = 3.14159265359;
+const uint MAX_SAMPLES = 1024u;
 
 // Output fragment color
 out vec4 finalColor;
@@ -93,7 +93,7 @@ vec2 IntegrateBRDF(float NdotV, float roughness)
     vec3 V = vec3(sqrt(1.0 - NdotV*NdotV), 0.0, NdotV);
     vec3 N = vec3(0.0, 0.0, 1.0);
 
-    for (int i = 0; i < MAX_SAMPLES; i++)
+    for (uint i = 0u; i < MAX_SAMPLES; i++)
     {
         // Generate a sample vector that's biased towards the preferred alignment direction (importance sampling)
         

examples/models/resources/shaders/irradiance.fs

@@ -9,7 +9,7 @@
 #version 330
 
 // Input vertex attributes (from vertex shader)
-in vec3 fragPos;
+in vec3 fragPosition;
 
 // Input uniform values
 uniform samplerCube environmentMap;
@@ -23,7 +23,7 @@ out vec4 finalColor;
 void main()
 {
     // The sample direction equals the hemisphere's orientation
-    vec3 normal = normalize(fragPos);
+    vec3 normal = normalize(fragPosition);
 
     vec3 irradiance = vec3(0.0);  
 

examples/models/resources/shaders/prefilter.fs

@@ -11,7 +11,7 @@
 #define     CUBEMAP_RESOLUTION      1024.0
 
 // Input vertex attributes (from vertex shader)
-in vec3 fragPos;
+in vec3 fragPosition;
 
 // Input uniform values
 uniform samplerCube environmentMap;
@@ -79,7 +79,7 @@ vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness)
 void main()
 {
     // Make the simplyfying assumption that V equals R equals the normal 
-    vec3 N = normalize(fragPos);
+    vec3 N = normalize(fragPosition);
     vec3 R = N;
     vec3 V = R;