Java port of Doom-Engine?

[kpars]

Alright guys, Here’s the actual thread for KDoom, so all feedback for it should go there.

[deepthought]

@Agro

Yeah, things like OpenGL use ray tracing, which casts a ray for every pixel on the screen. Then it does all the polygon intersections with loads of stuff involving light sources and other stuff.

uhhh… noo…
Opengl doesn’t do anything with rays. Opengl projects primitives into 2d space and uses perspective correct texture mapping. Lighting is an approximation based on distance and angle, and shadows are a whole other hack.

[Longor1996]

@Agro

Yeah, things like OpenGL use ray tracing, which casts a ray for every pixel on the screen. Then it does all the polygon intersections with loads of stuff involving light sources and other stuff.

Ray casting is a “fake” 3D perspective because it only draws 1 ray for each vertical column of the screen. It finds any intersections, and based off of the distance from you to that “block” on the map, It will draw a line that is a certain height. The main disadvantage to this is that you can’t have sloped walls, jumping, free looking, etc. All of these problems are fixed when ray tracing is implemented.

If OpenGL would be a RayTracer we could have:

• Built in infinite Resolution for Curved Surfaces
• Built in Realtime Reflections (Mirror)
• Built in Realtime Refractions (Glass)
• Built in Realtime Ray Scene Traversal (Portal)
• etc. etc.

OpenGL is a library that takes primitives and draws them onto the screen using matrix projections, as deepthought said.

Have a nice day.

• Longor1996

[gimbal]

@kpars

The main reason I decided to make it Pseudo-3D was to give it a “Doomy” feel.
It’s probably a stupid reason, but I felt like this had a more “Doomy” atmosphere to work on than something using OpenGL. No idea why.

Its not a stupid reason at all, it is something different and well worth it to figure out how it worked; at the very least it is entertaining to do and get a prototype working, especially nowadays where you can just create a dumb, unoptimized and more readable version that does not need assembly to get it to perform well enough. I like to revisit the classic techniques myself and wonder how they did it back in the day.

[jediman]

@kpars

Entirely based off of raycasting.

I’m fairly sure The Cherno’s code is very similar to Notch’s Prelude of the Chambered (http://s3.amazonaws.com/ld48/index.html), and it doesn’t actually do any raycasting at all It’s all just perspective texture projection.

[kpars]

Thank you for that

And yes, I know The Cherno used Notch’s code. He never gave any credit, sadly.