// cube_vertex_shader.vs
#version 330 core

// Vertex Attributes
layout(location = 0) in vec3 aPos;       // Vertex position
layout(location = 1) in vec3 aNormal;    // Vertex normal
layout(location = 2) in vec2 aTexCoords; // Texture coordinates

// Uniform Matrices
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
uniform mat4 lightSpaceMatrix;

// Output to Fragment Shader
out VS_OUT {
    vec3 FragPos;            // Fragment position in world space
    vec3 Normal;             // Fragment normal in world space
    vec2 TexCoords;          // Texture coordinates
    vec4 FragPosLightSpace;  // Fragment position in light space
} fs_in;

void main()
{
    // Calculate fragment position in world space
    fs_in.FragPos = vec3(model * vec4(aPos, 1.0));
    
    // Calculate and normalize the normal vector in world space
    fs_in.Normal = mat3(transpose(inverse(model))) * aNormal;
    
    // Pass through texture coordinates
    fs_in.TexCoords = aTexCoords;
    
    // Calculate fragment position in light space for shadow mapping
    fs_in.FragPosLightSpace = lightSpaceMatrix * vec4(fs_in.FragPos, 1.0);
    
    // Final vertex position in clip space
    gl_Position = projection * view * vec4(fs_in.FragPos, 1.0);
}