From fc8d7fed3ccdf0998a7b9809aa825f2d14876b29 Mon Sep 17 00:00:00 2001
From: jvech <jmvalenciae@unal.edu.co>
Date: Fri, 16 Sep 2022 16:21:37 -0500
Subject: learn: 17. Multiple lights

---
 shaders/color.fsh | 127 ++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 114 insertions(+), 13 deletions(-)

(limited to 'shaders')

diff --git a/shaders/color.fsh b/shaders/color.fsh
index c2a8dc7..a0958ed 100644
--- a/shaders/color.fsh
+++ b/shaders/color.fsh
@@ -1,4 +1,5 @@
-# version 330 core
+#version 330 core
+#define NR_POINT_LIGHTS 4
 
 struct Material {
     sampler2D diffuse;
@@ -6,13 +7,41 @@ struct Material {
     float shininess;
 };
 
-struct Light {
+struct DirLight {
+    vec3 direction;
+
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+};
+
+struct PointLight {
     vec3 position;
+
+    float constant;
+    float linear;
+    float quadratic;
+
     vec3 ambient;
     vec3 diffuse;
     vec3 specular;
 };
 
+struct FlashLight {
+    vec3 position;
+    vec3 direction;
+
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+
+    float cutOff;
+    float outerCutOff;
+    float constant;
+    float linear;
+    float quadratic;
+};
+
 in vec3 Normal;
 in vec3 FragPos;
 in vec2 TexCoords;
@@ -21,24 +50,96 @@ out vec4 FragColor;
 
 uniform vec3 viewPos;
 uniform Material material;
-uniform Light light;
+uniform DirLight dirLight;
+uniform PointLight pointLight[NR_POINT_LIGHTS];
+uniform FlashLight flashLight;
 
-void main()
+vec3 calcDirLight(DirLight light, vec3 normal, vec3 viewDir)
 {
-    // ambient
+    vec3 lightDir = normalize(-light.direction);
+    // diffuse
+    float diff = max(dot(normal, lightDir), 0.0);
+    // specular
+    vec3 reflectDir = reflect(-lightDir, normal);
+    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
+
     vec3 ambient = light.ambient * texture(material.diffuse, TexCoords).rgb;
-    
+    vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoords).rgb;
+    vec3 specular = light.specular * spec * texture(material.specular, TexCoords).rgb;
+
+    return (ambient + diffuse + specular);
+}
+
+vec3 calcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
+{
+    vec3 lightDir = normalize(light.position - fragPos);
     // diffuse
-    vec3 norm = normalize(Normal);
-    vec3 lightDir = normalize(light.position - FragPos);
-    float diff = max(dot(norm, lightDir), 0.0);
+    float diff = max(dot(normal, lightDir), 0.0);
+
+    //specular
+    vec3 reflectDir = reflect(-lightDir, normal);
+    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
+
+    //attenuation
+    float dist = length(light.position - fragPos);
+    float attenuation = 1.0 / (light.constant + light.linear * dist + 
+                        light.quadratic * (dist * dist));
+
+    vec3 ambient = light.ambient * texture(material.diffuse, TexCoords).rgb;
     vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoords).rgb;
+    vec3 specular = light.specular * spec * texture(material.specular, TexCoords).rgb;
 
-    // specular
-    vec3 viewDir = normalize(viewPos - FragPos);
-    vec3 reflectDir = reflect(-lightDir, norm);
+    ambient *= attenuation;
+    diffuse *= attenuation;
+    specular *= attenuation;
+
+    return ambient + diffuse + specular;
+}
+
+vec3 calcFlashLight(FlashLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
+{
+    vec3 lightDir = normalize(light.position - fragPos);
+    float theta = dot(lightDir, normalize(-light.direction));
+    float epsilon = light.cutOff - light.outerCutOff;
+    float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);
+
+    // diffuse
+    float diff = max(dot(normal, lightDir), 0.0);
+
+    //specular
+    vec3 reflectDir = reflect(-lightDir, normal);
     float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
+
+    //attenuation
+    float dist = length(light.position - fragPos);
+    float attenuation = 1.0 / (light.constant + light.linear * dist + 
+                        light.quadratic * (dist * dist));
+
+    vec3 ambient = light.ambient * texture(material.diffuse, TexCoords).rgb;
+    vec3 diffuse = light.diffuse * diff * texture(material.diffuse, TexCoords).rgb;
     vec3 specular = light.specular * spec * texture(material.specular, TexCoords).rgb;
 
-    FragColor = vec4((specular + ambient + diffuse), 1.0f);
+    diffuse *= attenuation * intensity;
+    specular *= attenuation * intensity;
+
+    return ambient + diffuse + specular;
+}
+
+void main()
+{
+    // properties
+    vec3 norm = normalize(Normal);
+    vec3 viewDir = normalize(viewPos - FragPos);
+
+    // 1. Directional light
+    vec3 result = calcDirLight(dirLight, norm, viewDir);
+
+    // 2. Point lights
+    for (int i = 0; i < NR_POINT_LIGHTS; i++)
+        result += calcPointLight(pointLight[i], norm, FragPos, viewDir);
+
+    // 3. Spot light
+    result += calcFlashLight(flashLight, norm, FragPos, viewDir);
+
+    FragColor = vec4(result, 1.0);
 }
-- 
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