PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a light-weight cotton jersey knit. It has low specularity (matte finish) and high flexibility. Unlike the stiff structure of a jacket, this fabric relies heavily on gravity and friction against the skin. It absorbs light rather than reflecting it, creating soft, diffuse gradients. - **Key Features:** - **Long Sleeves:** Crucial translation from the source to the target, as the target is currently wearing short sleeves. - **Ribbed Crew Neck:** A slightly wider neckline than the user's current maroon tee. - **Chest Logo:** Small minimalist bird/text logo on the upper left chest must be preserved and warped correctly over the pectoral muscle. - **Relaxed Fit:** The source is a "regular/relaxed" fit, whereas the user's current shirt is "slim/muscle" fit. The generated mesh must capture this looser volume. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** - **Right Arm (Raised):** Physics simulation is critical here. The long sleeve must slide down the forearm due to gravity, creating significant "accordion" bunching at the elbow and shoulder accumulation. The fabric under the armpit must be pulled taut (high tension) due to the abduction of the arm. - **Left Arm (Relaxed):** The sleeve should drape vertically with a slight cylinder shape, bunching slightly at the wrist where it meets the hand. - **Torso:** The garment must hang loosely over the abdominals, avoiding the "vacuum-sealed" look of the current maroon shirt. The hemline should fall naturally over the hips, obscuring the waistband of the beige shorts. - **Occlusion Handling:** - **Neck/Chin:** The new collar must sit naturally around the neck base. The user's jawline shadow must be re-projected onto the new fabric. - **Waist:** The new shirt is longer than the current one; ensure the beige shorts are masked out where the new hemline overlaps them. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The user image features a strong, hard directional light source coming from the **viewer's left** (user's right), casting deep, sharp shadows on the viewer's right. - The new sage green fabric must show high luminance/exposure on the right shoulder and pectoral. - Deep, sharp fall-off shadows must be rendered on the left side of the torso and underneath the raised right arm. - **Color Calibration:** The user environment has a warm, yellow/orange ambient tone. The cool sage green of the source cloth must be color-graded with a slight warm overlay to match the ambient temperature of the room, preventing the "sticker effect." PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's face, skin tone, ears, and the beige cap are strictly immutable. The boundary between the neck skin and the new t-shirt collar must be blended seamlessly. - **Body Integrity:** Do not alter the user's shoulder width or muscle definition. While the clothing fit changes from slim to relaxed, the underlying skeletal structure and pose must remain exactly as is. Do not slim the waist.