Add OpenGL backend project and third phase plan

MVS/OpenGL/Shaders/fragmentshader.glsl

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+#version 330 core
+out vec4 FragColor;
+
+struct Material {
+     sampler2D texture_diffuse1; 
+     sampler2D texture_diffuse2; 
+     sampler2D texture_diffuse3; 
+     sampler2D texture_specular1; 
+     sampler2D texture_specular2;
+
+    float shininess;
+}; 
+
+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;
+};
+
+#define NR_POINT_LIGHTS 10
+
+in vec3 FragPos;
+in vec3 Normal;
+in vec2 TexCoords;
+
+uniform int PointLightNum;
+uniform vec3 viewPos;
+uniform DirLight dirLight;
+uniform PointLight pointLights[NR_POINT_LIGHTS];
+
+uniform Material material;
+
+// function prototypes
+vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir);
+vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir);
+
+void main()
+{    
+    // properties
+    vec3 norm = normalize(Normal);
+    vec3 viewDir = normalize(viewPos - FragPos);
+    
+    // == =====================================================
+    // Our lighting is set up in 3 phases: directional, point lights and an optional flashlight
+    // For each phase, a calculate function is defined that calculates the corresponding color
+    // per lamp. In the main() function we take all the calculated colors and sum them up for
+    // this fragment's final color.
+    // == =====================================================
+    // phase 1: directional lighting
+    vec3 result = CalcDirLight(dirLight, norm, viewDir);
+    // phase 2: point lights
+    for(int i = 0; i < PointLightNum; i++)
+    {
+         result += CalcPointLight(pointLights[i], norm, FragPos, viewDir);   
+    }
+ 
+    // phase 3: spot light   
+
+    FragColor = vec4(result, 1.0);
+}
+
+// calculates the color when using a directional light.
+vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir)
+{
+    vec3 lightDir = normalize(-light.direction);
+    // diffuse shading
+    float diff = max(dot(normal, lightDir), 0.0);
+    // specular shading
+    vec3 reflectDir = reflect(-lightDir, normal);
+    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
+    // combine results
+    vec3 ambient = light.ambient * vec3(texture(material.texture_diffuse1, TexCoords));
+    vec3 diffuse = light.diffuse * diff * vec3(texture(material.texture_diffuse1, TexCoords));
+    vec3 specular = light.specular * spec * vec3(texture(material.texture_specular1, TexCoords));
+    return (ambient + diffuse + specular);
+}
+
+// calculates the color when using a point light.
+vec3 CalcPointLight(PointLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
+{
+    vec3 lightDir = normalize(light.position - fragPos);
+    // diffuse shading
+    float diff = max(dot(normal, lightDir), 0.0);
+    // specular shading
+    vec3 reflectDir = reflect(-lightDir, normal);
+    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
+    // attenuation
+    float distance = length(light.position - fragPos);
+    float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));  
+    attenuation = min(attenuation, 1.0f);
+    // combine results
+    vec3 ambient = light.ambient * vec3(texture(material.texture_diffuse1, TexCoords));
+    vec3 diffuse = light.diffuse * diff * vec3(texture(material.texture_diffuse1, TexCoords));
+    vec3 specular = light.specular * spec * vec3(texture(material.texture_specular1, TexCoords));
+    
+    ambient *= attenuation;
+    diffuse *= attenuation;
+    specular *= attenuation;
+    return (ambient + diffuse + specular);
+}

MVS/OpenGL/Shaders/vertexshader.glsl

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+#version 330 core
+layout (location = 0) in vec3 inPos;
+layout (location = 1) in vec3 inNormal;
+layout (location = 2) in vec2 inTexCoords;
+
+
+out vec2 TexCoords;
+out vec3 FragPos;
+out vec3 Normal;
+
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
+
+void main()
+{
+	FragPos = vec3(model * vec4(inPos ,1.0f));
+	Normal = mat3(transpose(inverse(model))) * inNormal;
+	gl_Position = projection * view * vec4(FragPos,1.0);
+	TexCoords = inTexCoords;
+}