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vllm-omni/vllm_omni/model_extras/mammothmodal2_preview.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from __future__ import annotations
from typing import Any
# AR image-grid patch size (pixels per visual token). Mirrors the constant the
# bespoke MammothModa2 example used to convert image dimensions -> AR grid dims.
_PATCH_SIZE = 16
_AR_SYSTEM_PROMPT = "You are a helpful image generator."
def build_text_to_image_prompt(
prompt: str,
negative_prompt: str | None,
height: int | None = None,
width: int | None = None,
) -> dict[str, Any]:
"""Build the MammothModa2 AR-stage prompt for text-to-image generation.
Reproduces the prompt string and the structural ``additional_information``
that the former bespoke example (``run_mammothmoda2_t2i.py``) constructed,
deriving the AR image grid from ``height`` / ``width``.
Model-specific sampling knobs (``text_guidance_scale``, ``cfg_range``,
``num_inference_steps``) flow separately via ``extra_body`` -> ``extra_args``.
Config-derived token ids (``eol_token_id``, ``visual_token_start_id``,
``visual_token_end_id``, ``visual_ids``) are sourced inside the AR stage
rather than passed by the caller -- see the ar2dit stage input processor.
MammothModa2 t2i uses classifier-free guidance via ``text_guidance_scale``
and has no explicit negative-prompt path, so ``negative_prompt`` is accepted
for signature compatibility but not injected.
"""
h = height or 1024
w = width or 1024
ar_height = h // _PATCH_SIZE
ar_width = w // _PATCH_SIZE
return {
"prompt": (
f"<|im_start|>system\n{_AR_SYSTEM_PROMPT}<|im_end|>\n"
f"<|im_start|>user\n{prompt}<|im_end|>\n"
"<|im_start|>assistant\n"
f"<|image start|>{ar_width}*{ar_height}<|image token|>"
),
"additional_information": {
"omni_task": ["t2i"],
"ar_width": [ar_width],
"ar_height": [ar_height],
"image_height": [h],
"image_width": [w],
},
}
MAMMOTHMODA2_PREVIEW_EXTRA_BODY_PARAMS = frozenset(
{
"text_guidance_scale",
"cfg_range",
# MammothModa2's DiT stage consumes inputs via the kwargs interface rather
# than OmniDiffusionRequest, so the standard --num-inference-steps flag does
# not reach it; it is routed through extra_body like the CFG knobs.
"num_inference_steps",
}
)
MAMMOTHMODA2_PREVIEW_EXTRA_OUTPUT_PARAMS = frozenset()
MAMMOTHMODA2_PREVIEW_INIT_EXTRA_ARGS_FOR_NON_DIFFUSION_STAGES = True