got a scaling window going, yay

[eniko@mastodon.gamedev.place]

@bnut you could conceivably do the same thing with the bottom edges but you'd have to step vertically in your inner loops which could trash cache locality

[photex@icosahedron.website]

@mmby @eniko familiar feels! But the main difference for me is that I go one step further and wonder why I shouldn’t just target an sbc and make my game a bespoke single use OS image. Bonus points for something that has an fpga so that the rasterizer gets implemented in hardware.

[eniko@mastodon.gamedev.place]

@photex @mmby i think software rasterizing is like programming language development. you create a handful of primitives and it feels incredibly powerful because its like "i could make anything with these!"

[eniko@mastodon.gamedev.place]

@bnut hm, interesting thought!

[photex@icosahedron.website]

@eniko @mmby VMs too! It’s such a great experience.

[eniko@mastodon.gamedev.place]

@bnut i think the calculations for all the weights/attribute values for each edge tile might still be more expensive than just stepping

[nicklockwood@mastodon.social]

@eniko why stop at 4x4? - or rather, why two fixed levels rather than a full quad-tree structure?

[nicklockwood@mastodon.social]

@eniko btw, for the corners between tiles, do you test that point 4x per triangle edge (once for each neigboring tile) or can you share the result between tiles?

[eniko@mastodon.gamedev.place]

@bnut this isn't lerping anything. it calculates all the stepping increments once up-front and then does addition across the entire bounding box to get the weights and attribute values

i guess maybe you could step them along with the bresenham? 🤔

[eniko@mastodon.gamedev.place]

@nicklockwood you can share the result but i'm not, since calculating the corners is only 3 additions and most of the work is in checking them all together, and sharing the corners is more bookkeeping and would make fully covered tiled a little less common

[nicklockwood@mastodon.social]

@eniko is the gourard shading just bilinear interpolation of vertex colors supplied by the caller, or do you actually have a lighting model on top?

And if so, what do you do in flat shading mode if a triangle has different vertex colors?

[eniko@mastodon.gamedev.place]

@bnut that could work 🤔

i've done a lot of work on this and am ready to stop though so i'm not gonna try it >_>

[eniko@mastodon.gamedev.place]

@nicklockwood it's harder to write a generic dynamically sized hierarchical system that's also fully optimized. also, at 32x32 even at 8k resolution that's only 240x135 meta tiles, so i'm not sure it has a ton of advantage

[eniko@mastodon.gamedev.place]

@nicklockwood it's just bilinear interpolation. the way it works is that vertices can have any number of interpolated attributes, so in gouraud it has r, g, and b attributes. in flat color mode it doesn't actually step the attributes at all and just pipes the color value straight through

[eniko@mastodon.gamedev.place]

@bnut a simpler optimization would be to count left sided vs right sided verts and switch iteration direction based on that

[eniko@mastodon.gamedev.place]

ok ok one more. i'm checking right sidedness by counting vertices on the right side of the bounding box center, and if it is a right sided triangle i change the horizontal tile iteration from left-to-right to right-to-left

so now the left image's triangle doesn't do a bunch of extra work

[jens@social.finkhaeuser.de]

@eniko This reminds me so much of a book I still have somewhere with assembly drawing routines from the demo scene of the late 90s.

Pro: taught me how to rasterize a curved line.

Con: I forgot everything.

I also don't remember the target platform.