Added PBR required resources

examples/models/resources/shaders/irradiance.fs

@@ -0,0 +1,58 @@
+/*******************************************************************************************
+*
+*   rPBR [shader] - Irradiance cubemap fragment shader
+*
+*   Copyright (c) 2017 Victor Fisac
+*
+**********************************************************************************************/
+
+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec3 fragPos;
+
+// Input uniform values
+uniform samplerCube environmentMap;
+
+// Constant values
+const float PI = 3.14159265359f;
+
+// Output fragment color
+out vec4 finalColor;
+
+void main()
+{
+    // The sample direction equals the hemisphere's orientation
+    vec3 normal = normalize(fragPos);
+
+    vec3 irradiance = vec3(0.0);  
+
+    vec3 up = vec3(0.0, 1.0, 0.0);
+    vec3 right = cross(up, normal);
+    up = cross(normal, right);
+
+    float sampleDelta = 0.025f;
+    float nrSamples = 0.0f; 
+
+    for (float phi = 0.0; phi < 2.0*PI; phi += sampleDelta)
+    {
+        for (float theta = 0.0; theta < 0.5*PI; theta += sampleDelta)
+        {
+            // Spherical to cartesian (in tangent space)
+            vec3 tangentSample = vec3(sin(theta)*cos(phi), sin(theta)*sin(phi), cos(theta));
+            
+            // tangent space to world
+            vec3 sampleVec = tangentSample.x*right + tangentSample.y*up + tangentSample.z*normal; 
+
+            // Fetch color from environment cubemap
+            irradiance += texture(environmentMap, sampleVec).rgb*cos(theta)*sin(theta);
+            nrSamples++;
+        }
+    }
+
+    // Calculate irradiance average value from samples
+    irradiance = PI*irradiance*(1.0/float(nrSamples));
+
+    // Calculate final fragment color
+    finalColor = vec4(irradiance, 1.0);
+}