graphics: Add basic image based ambient lighting.

1 files changed, 9 insertions, 5 deletions

diff --git a/data/shaders/pbr-frag.glsl b/data/shaders/pbr-frag.glsl
index c474981..fff725a 100644
--- a/data/shaders/pbr-frag.glsl
+++ b/data/shaders/pbr-frag.glsl
@@ -47,9 +47,9 @@ out vec4 fragColor;
 
 uniform Material material;
 uniform Light lights[MAX_LIGHTS];
-uniform vec4 ambientLight;
 uniform bool vertexColored;
 uniform vec3 cameraPosition;
+uniform samplerCube skybox;
 uniform sampler2D baseColorTexture;
 uniform sampler2D metallicRoughnessTexture;
 uniform sampler2D normalTexture;
@@ -244,6 +244,7 @@ void main(void) {
   float metallic = materialMetallic();
   float roughness = materialRoughness();
   vec3 normal = materialNormal();
+  vec3 reflection = reflect(-viewDirection, normal);
   // The "raw" albedo has an alpha channel which we need to preserve
   // so that we can apply the desired alpha blending method at the
   // end, but it is completely ignored for lighting calculations.
@@ -356,11 +357,14 @@ void main(void) {
   // The emissive texture says which fragments emit light.  We simply
   // add this light value to the color accumulator.
   color += materialEmissive();
-  // Apply simple ambient lighting.  The affect of the ambient light
-  // is dampened by the ambient occlusion factor.
+  // Apply image based ambient lighting.  The affect of the ambient
+  // light is dampened by the ambient occlusion factor.
   //
-  // TODO: Use image based lighting.
-  color += ambientLight.rgb * albedo * ambientOcclusion;
+  // TODO: Use fancy PBR equations instead of these basic ones.
+  float fresnel = pow(1.0 - clamp(dot(viewDirection, normal), 0.0, 1.0), 5);
+  vec3 ambientDiffuse = textureCube(skybox, normal).rgb;
+  vec3 ambientSpecular = textureLod(skybox, reflection, roughness * 7.0).rgb;
+  color += (ambientDiffuse * albedo + ambientSpecular * fresnel) * ambientOcclusion;
   // Apply Reinhard tone mapping to convert our high dynamic range
   // color value to low dynamic range.  All of the lighting
   // calculations stacked on top of each other is likely to create