Welcome to the community! It's great to have you here.
Regarding your question about the equation for PSX's vertex color and texture color blending, the PlayStation's GPU, often referred to as the GTE (Geometry Transformation Engine), had specific fixed-function blending operations. Unfortunately, it doesn't have a shader-based programmable pipeline like modern GPUs. The blending operations were performed in hardware.
If you want to implement something similar in Unreal Engine 4, you may need to use the engine's material system to achieve the desired visual effects. UE4 uses a shader-based approach, and you'd typically handle color blending in the material editor using nodes.
For a more accurate representation of the PSX's rendering techniques, you might need to explore custom shaders or post-processing effects. Keep in mind that replicating the exact look of PSX graphics in a modern engine might involve some creative interpretation, as the rendering techniques and capabilities have evolved significantly.
If you have specific details or effects from the PSX you're looking to achieve, feel free to provide more information, and I can offer more targeted advice. Cheers!
