package main

import "github.com/go-gl/gl/v4.1-core/gl"

type VertexBuffer struct {
	bufferId uint32
}

func NewVertexBuffer(data []float32) *VertexBuffer {
	var bufferID uint32
	gl.GenBuffers(1, &bufferID)
	gl.BindBuffer(gl.ARRAY_BUFFER, bufferID)
	gl.BufferData(gl.ARRAY_BUFFER, len(data)*4, gl.Ptr(data), gl.STATIC_DRAW)

	return &VertexBuffer{bufferId: bufferID}
}

func (vb *VertexBuffer) Bind() {
	gl.BindBuffer(gl.ARRAY_BUFFER, vb.bufferId)
}

func (vb *VertexBuffer) Unbind() {
	gl.BindBuffer(gl.ARRAY_BUFFER, 0)
}

type VertexArray struct {
	ID uint32
}

func NewVertexArray() *VertexArray {
	var id uint32
	gl.GenVertexArrays(1, &id)
	return &VertexArray{ID: id}
}

func (va *VertexArray) AddBuffer(vb *VertexBuffer, layout []int32) {
	va.Bind()
	vb.Bind()
	stride := int32(0)
	for _, size := range layout {
		stride += size
	}
	stride *= 4 // Each float is 4 bytes

	offset := uintptr(0)
	for i, size := range layout {
		gl.EnableVertexAttribArray(uint32(i))
		gl.VertexAttribPointer(uint32(i), size, gl.FLOAT, false, stride, gl.PtrOffset(int(offset)))
		offset += uintptr(size * 4)
	}
}

func (va *VertexArray) Bind() {
	gl.BindVertexArray(va.ID)
}

func (va *VertexArray) Unbind() {
	gl.BindVertexArray(0)
}