Mario García Lázaro

As the player moves around, cars are constantly created and deleted to give the appearance of a busy city. For gta3, Vice & SA, my code places cars at about 70m from the player if they would be in view of the camera. They get removed at around 90m. Cars that are ‘off screen’ get placed at around 15m and removed at 25m. In the image (thanks, electromaximus) cars are created at the green and removed at the red lines. When the player looks ‘behind’, cars straight ahead would be considered ‘off screen’ and removed. Speedrunners use this to clear the road ahead of them. For SA, I changed the rule so that cars would have to be off-screen for at least 2 seconds to be removed. This fixed it. My code looked for road nodes at the appropriate distance to create cars and that didn’t already have cars nearby. Sometimes there were no suitable nodes which could result in empty or unusually busy streets. Cars further than 20m away use reduced physics/collision. In this state, cars do not detect collisions and would drive straight through walls. When the player gets close, the full physics is switched on. You can notice this happening as cars drop a little until the suspension settles. Cars don’t switch back to the reduced physics state.