From 8c2386442a60bac743a6e80d5ba024efe92958c5 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Thu, 23 Sep 2021 19:11:29 -0400
Subject: graphics: light: Add intensity field.

---
 chickadee/graphics/light.scm | 24 +++++++++++++++++-------
 data/shaders/pbr-frag.glsl   |  5 +++--
 data/shaders/phong-frag.glsl |  5 +++--
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/chickadee/graphics/light.scm b/chickadee/graphics/light.scm
index d217f56..25fd17e 100644
--- a/chickadee/graphics/light.scm
+++ b/chickadee/graphics/light.scm
@@ -40,10 +40,12 @@
             light-position
             light-direction
             light-color
+            light-intensity
             light-cut-off
             set-light-position!
             set-light-direction!
             set-light-color!
+            set-light-intensity!
             set-light-cut-off!))
 
 ;; Maximum number of lights supported by our shaders.
@@ -57,7 +59,8 @@
   (float-vec3 position light-position set-light-position!)
   (float-vec3 direction light-direction set-light-direction!)
   (float-vec4 color light-color set-light-color!)
-  (float cut-off light-cut-off set-light-cut-off!))
+  (float intensity light-intensity set-light-intensity!)
+  (float cut-off light-cut-off %set-light-cut-off!))
 
 (define %disabled-light (make-light #:enabled #f))
 
@@ -77,27 +80,34 @@
 (define (spot-light? light)
   (eq? (light-type light) 'spot))
 
+(define (set-light-cut-off! light cut-off)
+  (%set-light-cut-off! light (cos cut-off)))
+
 (define* (make-point-light #:key (position (vec3 0.0 0.0 0.0))
-                           (color black))
+                           (color black) (intensity 1.0))
   (make-light #:enabled #t
               #:type 0
               #:position position
-              #:color color))
+              #:color color
+              #:intensity intensity))
 
 (define* (make-directional-light #:key (direction (vec3 0.0 -1.0 0.0))
-                                 (color black))
+                                 (color black) (intensity 1.0))
   (make-light #:enabled #t
               #:type 1
               #:direction direction
-              #:color color))
+              #:color color
+              #:intensity intensity))
 
 (define* (make-spot-light #:key (position (vec3 0.0 0.0 0.0))
                           (direction (vec3 0.0 0.0 -1.0))
                           (color black)
-                          (cut-off (/ pi 4.0)))
+                          (cut-off (/ pi 4.0))
+                          (intensity 1.0))
   (make-light #:enabled #t
               #:type 2
               #:position position
               #:direction direction
               #:color color
-              #:cut-off (cos cut-off)))
+              #:cut-off (cos cut-off)
+              #:intensity intensity))
diff --git a/data/shaders/pbr-frag.glsl b/data/shaders/pbr-frag.glsl
index fff725a..e6bcdc5 100644
--- a/data/shaders/pbr-frag.glsl
+++ b/data/shaders/pbr-frag.glsl
@@ -20,6 +20,7 @@ struct Light {
   vec3 position;
   vec3 direction;
   vec4 color;
+  float intensity;
   float cutOff;
 };
 
@@ -210,14 +211,14 @@ vec3 lightDirection(Light light) {
 vec3 lightAttenuate(Light light) {
   float distance = length(light.position - fragWorldPos);
   float attenuation = 1.0 / (distance * distance);
-  return light.color.rgb * attenuation;
+  return light.color.rgb * light.intensity * attenuation;
 }
 
 vec3 lightRadiance(Light light, vec3 direction) {
   if(light.type == 0) { // point light
     return lightAttenuate(light);
   } else if(light.type == 1) { // directional light
-    return light.color.rgb;
+    return light.color.rgb * light.intensity;
   } else if(light.type == 2) { // spot light
     float theta = dot(direction, normalize(-light.direction));
     // Spot lights only shine light in a specific conical area.
diff --git a/data/shaders/phong-frag.glsl b/data/shaders/phong-frag.glsl
index 9c86c83..b07c8b0 100644
--- a/data/shaders/phong-frag.glsl
+++ b/data/shaders/phong-frag.glsl
@@ -13,6 +13,7 @@ struct Light {
   vec3 position;
   vec3 direction;
   vec4 color;
+  float intensity;
   float cutOff;
 };
 
@@ -71,14 +72,14 @@ vec3 lightDirection(Light light) {
 vec3 lightAttenuate(Light light) {
   float distance = length(light.position - fragWorldPos);
   float attenuation = 1.0 / (distance * distance);
-  return light.color.rgb * attenuation;
+  return light.color.rgb * light.intensity * attenuation;
 }
 
 vec3 lightRadiance(Light light, vec3 direction) {
   if(light.type == 0) { // point light
     return lightAttenuate(light);
   } else if(light.type == 1) { // directional light
-    return light.color.rgb;
+    return light.color.rgb * light.intensity;
   } else if(light.type == 2) { // spot light
     float theta = dot(direction, normalize(-light.direction));
     // Spot lights only shine light in a specific conical area.
-- 
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