diff --git a/packages/ludic.render3d/gpu_vk_res.ludic b/packages/ludic.render3d/gpu_vk_res.ludic
new file mode 100644
index 00000000..c46925dd
--- /dev/null
+++ b/packages/ludic.render3d/gpu_vk_res.ludic
@@ -0,0 +1,39 @@
+# gpu_vk_res.ludic — the Vulkan backend's resources in the renderer's vocabulary: the formats,
+# and next the textures, buffers, samplers and pipelines gpu.ludic's handles stand for.
+#
+# gpu.ludic speaks OpenGL's names for formats, filters and blend factors, so this half of the
+# backend does too, and is only compiled inside render3d (which names Gl.*). gpu_vk.ludic - the
+# device, memory and one-shot commands - is pure Vulkan and runs on its own (vk_device.ludic).
+
+# ---- formats ------------------------------------------------------------------------------
+# The renderer names formats the way OpenGL does (they are gpu.ludic's vocabulary); these turn
+# one into the Vulkan image format that holds it. Three-channel formats have no widely
+# supported Vulkan image format, so they are stored with four and expanded on upload.
+function gvk_format(ifmt: int) -> int {
+  if ifmt == GL_RGBA8 or ifmt == GL_RGB8 { return VK_FORMAT_R8G8B8A8_UNORM }
+  if ifmt == GL_SRGB8_ALPHA8 or ifmt == GL_SRGB8 { return VK_FORMAT_R8G8B8A8_SRGB }
+  if ifmt == GL_R8 { return VK_FORMAT_R8_UNORM }
+  if ifmt == GL_RG8 { return VK_FORMAT_R8G8_UNORM }
+  if ifmt == GL_R16 { return VK_FORMAT_R16_UNORM }
+  if ifmt == GL_RG16 { return VK_FORMAT_R16G16_UNORM }
+  if ifmt == GL_RGBA16 or ifmt == GL_RGB16 { return VK_FORMAT_R16G16B16A16_UNORM }
+  if ifmt == GL_RG16F { return VK_FORMAT_R16G16_SFLOAT }
+  if ifmt == GL_RGBA16F or ifmt == GL_RGB16F { return VK_FORMAT_R16G16B16A16_SFLOAT }
+  if ifmt == GL_R32F { return VK_FORMAT_R32_SFLOAT }
+  if ifmt == GL_RGBA32F { return VK_FORMAT_R32G32B32A32_SFLOAT }
+  if ifmt == GL_DEPTH_COMPONENT32F or ifmt == GL_DEPTH_COMPONENT24 { return VK_FORMAT_D32_SFLOAT }
+  return VK_FORMAT_UNDEFINED
+}
+function gvk_is_depth(ifmt: int) -> bool { return ifmt == GL_DEPTH_COMPONENT32F or ifmt == GL_DEPTH_COMPONENT24 }
+# channels the Vulkan image stores per texel
+function gvk_channels(ifmt: int) -> int {
+  if ifmt == GL_R8 or ifmt == GL_R16 or ifmt == GL_R32F or gvk_is_depth(ifmt) { return 1 }
+  if ifmt == GL_RG8 or ifmt == GL_RG16 or ifmt == GL_RG16F { return 2 }
+  return 4
+}
+# bytes per channel the Vulkan image stores
+function gvk_channel_bytes(ifmt: int) -> int {
+  if ifmt == GL_RGBA8 or ifmt == GL_RGB8 or ifmt == GL_SRGB8_ALPHA8 or ifmt == GL_SRGB8 or ifmt == GL_R8 or ifmt == GL_RG8 { return 1 }
+  if ifmt == GL_R32F or ifmt == GL_RGBA32F or gvk_is_depth(ifmt) { return 4 }
+  return 2
+}
diff --git a/packages/ludic.render3d/r3d.ludic b/packages/ludic.render3d/r3d.ludic
index dbece3f6..1fc70e5f 100644
--- a/packages/ludic.render3d/r3d.ludic
+++ b/packages/ludic.render3d/r3d.ludic
@@ -4,6 +4,8 @@
 # ============================================================================
 import "fmath.ludic"
 import "gpu.ludic"
+import "gpu_vk.ludic"
+import "gpu_vk_res.ludic"
 import "prof.ludic"
 import "programs.ludic"
 import "texture.ludic"