English Amiga Board - View Single Post - How did games like Starglider 2 get such a high frame rate?

deimos · 09 August 2018, 15:42

I'm playing around with some 3D graphics code at the moment, thinking about maybe doing something more with it, if only I can make it fast enough.

I'm animating a familiar looking chequered ball made up of 128 polygons. it's just moving around the screen while rotating around its centre. About half of the polygons get back face culled and so aren't rendered, leaving me with with around 64 to draw to the screen. I'm not currently doing any hidden surface removal apart from the backface culling, not even depth sorting. And it looks ok, but it's just way too slow.

I'm getting less than 2 fps. I want more like 8.

I'm only doing rotate and translate of the object at the moment, the camera is fixed. I'm doing a 3x3 matrix translation for the rotation, 2.14 fixed point maths (in assembly language for the multiplies), then translating it and doing the division for the perspective view. I'm not doing 4x4 matrices at the moment because they're not needed with a fixed camera.

From the timings I've done, I know I spend 1/3 of my time doing the moving the ball and doing the 3D calculations, and about 2/3 of the time drawing the polygons. Drawing the polygons roughly splits into half of the time tracking the edges and half the time drawing horizontal lines from one side of the polygon to the other, making the whole split approx 1/3 3D calculations, 1/3 2D calculations 1/3 writing to screen memory.

So, even if I continue optimising my code and get it running twice as fast, I still won't be anywhere near my goal.

Does anyone know what tricks games like Starglider 2 did back in the day to get such a high framerate?

09 August 2018, 15:42	#1
deimos It's coming back! Join Date: Jul 2018 Location: comp.sys.amiga Posts: 762	How did games like Starglider 2 get such a high frame rate? I'm playing around with some 3D graphics code at the moment, thinking about maybe doing something more with it, if only I can make it fast enough. I'm animating a familiar looking chequered ball made up of 128 polygons. it's just moving around the screen while rotating around its centre. About half of the polygons get back face culled and so aren't rendered, leaving me with with around 64 to draw to the screen. I'm not currently doing any hidden surface removal apart from the backface culling, not even depth sorting. And it looks ok, but it's just way too slow. I'm getting less than 2 fps. I want more like 8. I'm only doing rotate and translate of the object at the moment, the camera is fixed. I'm doing a 3x3 matrix translation for the rotation, 2.14 fixed point maths (in assembly language for the multiplies), then translating it and doing the division for the perspective view. I'm not doing 4x4 matrices at the moment because they're not needed with a fixed camera. From the timings I've done, I know I spend 1/3 of my time doing the moving the ball and doing the 3D calculations, and about 2/3 of the time drawing the polygons. Drawing the polygons roughly splits into half of the time tracking the edges and half the time drawing horizontal lines from one side of the polygon to the other, making the whole split approx 1/3 3D calculations, 1/3 2D calculations 1/3 writing to screen memory. So, even if I continue optimising my code and get it running twice as fast, I still won't be anywhere near my goal. Does anyone know what tricks games like Starglider 2 did back in the day to get such a high framerate? Last edited by deimos; 21 November 2021 at 12:00.