Complete Story 3.2: Advanced Lighting and Multiple Lights

assets/cook_torrance_showcase.scene

@@ -79,6 +79,27 @@ sphere -2.0 -2.5 -6.0 0.7 plastic_red_normal     # Standard F0: 0.04
 sphere 0.0 -2.5 -6.0 0.7 plastic_red_glossy      # Higher F0: 0.08
 sphere 2.0 -2.5 -6.0 0.7 matte_white            # Lambert reference
 
+# ================================================
+# LIGHTING SYSTEM: OPTIMIZED FOR MATERIAL DEMONSTRATION
+# ================================================
+# Lighting setup specifically designed to showcase Cook-Torrance BRDF features
+# Emphasizes specular highlights, Fresnel effects, and material differences
+
+# Primary Directional Light: Strong directional light to emphasize Cook-Torrance vs Lambert differences
+# Positioned to create clear specular highlights across all spheres for material comparison
+# Strong intensity to make BRDF differences visible across roughness and metallic parameters
+light_directional -0.2 -0.8 -0.3 1.0 1.0 1.0 3.
+
+# Secondary Point Light: Positioned for specular highlight demonstration
+# Creates focused highlights that vary based on roughness and metallic parameters
+# Warm color temperature to enhance gold material appearance
+light_point 1.0 3.0 -2.0 1.0 0.9 0.7 3.
+
+# Soft Fill Light: Area light for subtle ambient illumination
+# Provides gentle fill lighting without overwhelming primary specular effects
+# Cool color temperature for color balance and depth
+light_area -3.0 1.0 -4.0 0.5 0.2 0.8 1.0 1.5 0.7 0.8 1.0 1.
+
 # ================================================
 # EDUCATIONAL NOTES AND LEARNING OBJECTIVES
 # ================================================
@@ -120,4 +141,13 @@ sphere 2.0 -2.5 -6.0 0.7 matte_white            # Lambert reference
 # - All materials use physically plausible parameter ranges
 # - Roughness limited to [0.01, 1.0] to prevent numerical instability
 # - F0 values appropriate for material types (0.04 typical for dielectrics)
-# - Scene layout optimized for educational comparison and visual learning
+# - Scene layout optimized for educational comparison and visual learning
+#
+# LIGHTING DESIGN FOR MATERIAL EDUCATION:
+# - Directional light: Creates consistent specular angles across all spheres
+# - Point light: Provides focused highlights that vary by surface properties
+# - Area light: Adds subtle ambient without masking material differences
+# - Light positioning emphasizes roughness gradients (smooth → rough)
+# - Color temperatures chosen to enhance metallic vs dielectric distinctions
+# - Intensities balanced to prevent overexposure while maintaining highlight visibility
+# - Multiple light types demonstrate how different illumination affects BRDF evaluation

assets/showcase_scene.scene

@@ -34,6 +34,24 @@ sphere 1.5 1.0 -5.5 0.9 warm_orange
 sphere 0.5 -1.5 -7.0 0.7 deep_purple
 sphere -1.5 -0.8 -7.5 0.5 cool_cyan
 
+# ================================================
+# LIGHTING SYSTEM: MULTI-LIGHT DEMONSTRATION
+# ================================================
+# Three-point lighting setup for professional scene illumination
+# Demonstrates multiple light types working together
+
+# Key Light: Primary illumination from front-right
+# Provides main illumination and defines primary shadows
+light_point 3.0 2.0 -1.0 1.0 0.95 0.8 4.0
+
+# Fill Light: Softer illumination from left to reduce harsh shadows
+# Balances the key light and provides secondary illumination
+light_point -2.0 1.0 -3.0 0.8 0.9 1.0 2.0
+
+# Rim Light: Directional light from behind for edge definition
+# Creates edge highlights and separates objects from background
+light_directional 0.3 -0.5 1.0 0.9 0.8 1.0 1.5
+
 # Educational Notes:
 # Scene Design Philosophy:
 # - 11 spheres total for complex intersection testing
@@ -55,4 +73,12 @@ sphere -1.5 -0.8 -7.5 0.5 cool_cyan
 # - Middle row adds depth and complexity
 # - Back row creates atmospheric perspective
 # - Color progression from warm (front) to cool (back) adds depth
-# - Size variation creates natural focal hierarchy
+# - Size variation creates natural focal hierarchy
+#
+# Multi-Light Design Philosophy:
+# - Key light: Warm white (1.0, 0.95, 0.8) for primary subject illumination
+# - Fill light: Cool white (0.8, 0.9, 1.0) for shadow balance and color variety
+# - Rim light: Neutral warm (0.9, 0.8, 1.0) for edge definition and depth
+# - Three-point lighting creates professional photographic quality
+# - Different light types demonstrate various illumination models
+# - Light intensity balanced to prevent overexposure while maintaining visibility

assets/simple_scene.scene

@@ -18,9 +18,20 @@ sphere 0.0 0.0 -5.0 1.0 red_sphere
 sphere 2.0 0.0 -6.0 0.8 blue_sphere
 sphere -1.5 1.0 -4.0 0.6 green_sphere
 
+# Lighting Section
+# Basic point light for educational visibility and material demonstration
+# Format: light_point pos_x pos_y pos_z color_r color_g color_b intensity
+light_point 2.0 2.0 -2.0 1.0 1.0 1.0 3.0
+
 # Educational Notes:
 # - Red sphere: Large central sphere for primary intersection testing
 # - Blue sphere: Offset sphere to test closest-hit logic
 # - Green sphere: Smaller sphere at different depth for depth testing
 # - All spheres positioned in front of camera (negative Z) for visibility
-# - Different radii to test intersection algorithm with varied sphere sizes
+# - Different radii to test intersection algorithm with varied sphere sizes
+#
+# Lighting Design:
+# - Single point light positioned above and to the right (2, 2, -2)
+# - White light (1.0, 1.0, 1.0) ensures neutral color representation
+# - Intensity 3.0 provides clear visibility without overexposure
+# - Light placement creates subtle shadows for depth perception