Batch_Sprites_BBox_Cropper.py

import torch

class Batch_Sprite_BBox_Cropper:
    """
    ComfyUI custom node:
    - Takes a batch of RGBA images (or RGB+MASK).
    - Alpha clamp: alpha <= (alpha_cutoff / 255) -> 0
    - Computes one global bounding box of visible pixels across the entire batch
    - Crops every image to the same bbox (spritesheet-safe)
    """

    @classmethod
    def INPUT_TYPES(cls):
        return {
            "required": {
                "images": ("IMAGE",),
                # User requirement: cutoff default = 10 (out of 255)
                "alpha_cutoff": ("INT", {"default": 10, "min": 0, "max": 255, "step": 1}),
                "verbose": ("BOOLEAN", {"default": True}),
            },
            # Optional: if you only have RGB image + separate alpha mask (common in ComfyUI)
            "optional": {
                "mask": ("MASK",),
            }
        }

    RETURN_TYPES = ("IMAGE", "INT", "INT", "INT", "INT", "INT", "INT")
    RETURN_NAMES = ("cropped_images", "left", "top", "right", "bottom", "crop_width", "crop_height")
    FUNCTION = "process"
    CATEGORY = "image/alpha"

    def process(self, images, alpha_cutoff=10, verbose=True, mask=None):
        """
        images: torch tensor [B, H, W, C] typically float32 in [0,1]
        mask:   torch tensor [B, H, W] or [H, W] in [0,1] (optional)
        """

        if not isinstance(images, torch.Tensor):
            raise TypeError("images must be a torch.Tensor")

        if images.dim() != 4:
            raise ValueError(f"images must be [B,H,W,C], got shape {tuple(images.shape)}")

        B, H, W, C = images.shape

        # Build RGBA tensor
        if C == 4:
            rgba = images.clone()
        elif C == 3:
            if mask is None:
                raise ValueError(
                    "Input images are RGB (C=3). Provide a MASK input or pass RGBA (C=4)."
                )
            # Normalize mask to [B,H,W]
            if mask.dim() == 2:
                mask_b = mask.unsqueeze(0).expand(B, -1, -1)
            elif mask.dim() == 3:
                mask_b = mask
            else:
                raise ValueError(f"mask must be [H,W] or [B,H,W], got shape {tuple(mask.shape)}")

            if mask_b.shape[0] != B or mask_b.shape[1] != H or mask_b.shape[2] != W:
                raise ValueError(
                    f"mask shape {tuple(mask_b.shape)} must match images batch/height/width {(B,H,W)}"
                )

            rgba = torch.cat([images, mask_b.unsqueeze(-1)], dim=-1).clone()
        else:
            raise ValueError(f"Expected images with 3 (RGB) or 4 (RGBA) channels, got C={C}")

        # 1) Alpha clamp: alpha <= (alpha_cutoff/255) -> 0
        threshold = float(alpha_cutoff) / 255.0
        alpha = rgba[..., 3]
        rgba[..., 3] = torch.where(alpha <= threshold, torch.zeros_like(alpha), alpha)

        # 2) Global bbox of visible pixels across batch (alpha > 0 after clamp)
        visible = rgba[..., 3] > 0  # [B,H,W] boolean
        if not torch.any(visible):
            # Nothing visible after clamp; skip crop
            if verbose:
                print(
                    f"[RGBABatchAlphaClampGlobalCrop] No visible pixels after clamp "
                    f"(alpha_cutoff={alpha_cutoff}). Returning unchanged RGBA."
                )
            left = 0
            top = 0
            right = W - 1
            bottom = H - 1
            crop_w = W
            crop_h = H
            return (rgba, left, top, right, bottom, crop_w, crop_h)

        # Union visibility across batch -> [H,W]
        union = torch.any(visible, dim=0)

        ys = torch.any(union, dim=1)  # [H]
        xs = torch.any(union, dim=0)  # [W]

        y_idx = torch.nonzero(ys, as_tuple=False).squeeze(1)
        x_idx = torch.nonzero(xs, as_tuple=False).squeeze(1)

        top = int(y_idx[0].item())
        bottom = int(y_idx[-1].item())
        left = int(x_idx[0].item())
        right = int(x_idx[-1].item())

        # 3) Crop all images to the same rect (inclusive right/bottom)
        cropped = rgba[:, top:bottom + 1, left:right + 1, :]

        crop_w = right - left + 1
        crop_h = bottom - top + 1

        if verbose:
            print(
                f"[RGBABatchAlphaClampGlobalCrop] alpha_cutoff={alpha_cutoff} "
                f"-> rect: left={left}, top={top}, right={right}, bottom={bottom} "
                f"(w={crop_w}, h={crop_h}), batch={B}"
            )

        return (cropped, left, top, right, bottom, crop_w, crop_h)


NODE_CLASS_MAPPINGS = {
    "Batch_Sprite_BBox_Cropper": Batch_Sprite_BBox_Cropper
}

NODE_DISPLAY_NAME_MAPPINGS = {
    "Batch_Sprite_BBox_Cropper": "Batch_Sprite_BBox_Cropper"
}