The foremost premise for the success of noninvasive volumetric myocardial transmembrane (TMP) imaging from body surface potential (BSP) recordings is a realistic yet efficient electrocardiographic model which relates volumetric myocardial TMP distribution to BSP distribution. With a view towards this inverse problem, the heart-torso representation and the associated TMP-to-BSP model should balance the accuracy of the model with the feasibility of TMP reconstruction. We present a novel coupled meshfree-BEM platform to this TMP-to-BSP modeling and perform electrocardiographic simulations of various cardiac conditions on personalized heart-torso structures. Simulated QRS integral maps, BSPMs and ECG leads are consistent with existent experimental studies, verifying the plausibility of the presented platform.