#version 460 core

layout (location = 0) in vec3 v_pos;
layout (location = 1) in vec3 v_normal;
layout (location = 2) in vec3 v_tangent;
layout (location = 3) in vec2 v_texcoord;

out VS_OUT {
    vec3 viewPos;
    vec2 texcoord;
    mat3 TBN;
} vs_out;

layout (std140, binding=0) uniform FrameMatrices {
    mat4 view;
    mat4 projection;
};
layout (location=0) uniform mat4 model;

void main() {
    gl_Position = projection * view * model * vec4(v_pos, 1.0);

    vs_out.texcoord = v_texcoord;

    // Gram-schmidt process for re-orthogonalizing the TBN vectors
    vec3 T = normalize(vec3(view * model * vec4(v_tangent, 0.0)));
    vec3 N = normalize(vec3(view * model * vec4(v_normal, 0.0)));
    T = normalize(T - dot(T, N) * N);
    vec3 B = cross(N, T);
    vs_out.TBN = mat3(T, B, N);

    vs_out.viewPos = (view * model * vec4(v_pos, 1.0)).xyz;
}