#version 430 core

struct DrawCtx {
    mat4 model;
    vec4 color[4];
};

layout(std430, binding = 0) buffer InstanceBuffer {
    DrawCtx instances[];
};

layout (location = 0) in vec3 a_position;
layout (location = 1) in vec2 a_texcoord;
layout (location = 2) in vec3 a_normal;

uniform mat4 u_vp;
// uniform mat4 u_model;

out vec3 v_fragpos;
out vec2 v_texcoord;
out vec3 v_normal;

void main() {
    // uint index = gl_GlobalInvocationID.x;

    mat4 u_model = instances[gl_InstanceID].model;

    v_texcoord = a_texcoord;
    v_normal = normalize(mat3(transpose(inverse(u_model))) * a_normal);
    vec4 fragpos4 = u_model * vec4(a_position, 1.0);

    v_fragpos = vec3(fragpos4);
    gl_Position = u_vp * fragpos4;
}