# gpu_vk_bc.ludic - a block-compressed texture's levels uploaded as they are: the GPU decodes BC
# blocks itself, so the bytes in the file are the bytes in video memory, a quarter of RGBA8's.

# every level of `tex` (made by gvk_tex_storage with its whole chain) from `data`, level l's
# blocks at offs[l] .. offs[l + 1]
function gvk_tex_upload_blocks(render3d_st: mut Render3dState, tex: int, w: int, h: int, levels: int, data: pointer, offs: words) -> bool {
  let n = offs[levels]
  let dst = gvk_staging(render3d_st, n, VK_BUFFER_USAGE_TRANSFER_SRC_BIT)
  if dst == null { print("r3d: vulkan: no staging buffer for a compressed upload");  return false }
  mem_copy(dst, data, n)
  let image = render3d_st.gvk_tex_image[tex]
  let cb = gvk_once_begin(render3d_st)
  gvk_barrier(render3d_st, cb, image, false, 0, levels, 1, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL)
  for l in 0 .. levels {
    let bic = gvk_tmp(render3d_st, VkBufferImageCopy_sizeof)
    Vk.zero(bic, VkBufferImageCopy_sizeof)
    let off: long = offs[l]
    Vk.put_i64(bic, VkBufferImageCopy_bufferOffset, off)
    Vk.put_i32(bic, VkBufferImageCopy_imageSubresource + VkImageSubresourceLayers_aspectMask, VK_IMAGE_ASPECT_COLOR_BIT)
    Vk.put_i32(bic, VkBufferImageCopy_imageSubresource + VkImageSubresourceLayers_mipLevel, l)
    Vk.put_i32(bic, VkBufferImageCopy_imageSubresource + VkImageSubresourceLayers_layerCount, 1)
    Vk.put_i32(bic, VkBufferImageCopy_imageExtent + VkExtent3D_width, max(w >> l, 1))
    Vk.put_i32(bic, VkBufferImageCopy_imageExtent + VkExtent3D_height, max(h >> l, 1))
    Vk.put_i32(bic, VkBufferImageCopy_imageExtent + VkExtent3D_depth, 1)
    Vk.cmd_copy_buffer_to_image(cb, render3d_st.gvk_st_buf, image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, bic)
  }
  gvk_barrier(render3d_st, cb, image, false, 0, levels, 1, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL)
  let ok = gvk_once_end(render3d_st, cb)
  gvk_staging_free(render3d_st)
  return ok
}