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** Sega Genesis 3D engine Day 2 ** Added solid filled triangles. Added colors ( full 15 color buffer ) . All code in C so far apart form the buffer clear and DMA buffer sending so should be some good speedups to come yet once line / triangle...

17,329 Aufrufe • vor 2 Monaten •via X (Twitter)

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** Sega Genesis 3D Engine Day 3 ** Blast Processing kicks In !! Converted the Line Drawing and Triangle drawing to 68k Assembly and gained 25% in the line drawing and 33% speedups in the triangle drawing vs C ( so far ) . The scheduler calculating the vertexs is still in C , just the drawing routines are now are in assembly . Possibly 5-10 % gains will come from the scheduler being in ASM also. The Line and Triangle drawing C code took some beating , it was surprising - particularly the line drawing to get a speed up over the C code in ASM. I guess its not too surprising as the C code was basically handling pointers and integers so I had to get exotic to find the speedups. Initially my ASM Line draw was 100% slower than the C code - the first pass conversion from C to ASM is always rough as its more about getting it working then refine later , but yeah 100% slower on first pass was brutal, after 4 hrs tweaking it was 25% faster than the C code so thats a good start - might get more yet. So added more squares and more triangles for load testing at the same frame rate. Its still not anything cohesive but right now focussing on performance in rendering to see how much can be pushed. As rendering will be the biggest cpu soak the faster that goes the better. The smaller triangles take about 1/3 the CPU time of the larger triangles at present so theres definately a fill rate limit vs the setup time to consider. The same would go for the squares been line framed - smaller ones would allow al lot more . #SGDK #SegaGenesis #SegaMegadrive

Shannon Birt

18,957 Aufrufe • vor 2 Monaten

** MEGA Parodius Scaling Effects Part 1 ** One of the big challenges with the Parodius Megadrive port is Stage 8's boss - The puffer-fish *Pooyan* with his full screen scaling effect. The goal is to be very close to the arcade (with extras on top ) so I thought lets tackle it head on to see how close we can get. I was also keen to jump into another scaling code rabit hole haha. Pyron pulled out all the stops and got me the source frames and reworked the BG tiles for this test - a big thankyou to him , Vector Orbitex is busy working on Stage 2 tracks so the team is working hard all round on this port. The MD has no sprite / background GFX scaling hardware , however the VDPs Vertical scroll can be updated per scanline to help vertical scaling on backgrounds, but there is a cpu cost to manage all the interupts so thats not free either. With the Horizontal scaling there is no help at all , apart from a semi-friendly packed pixel format for the cpu to work with, its not quite chunky format but better than planar format still for scaling. So its falls back to the 68k CPU to do all of the horizontal expansion which is the largest cpu cost. Basically drawing strips of either 1x, 2x, 3x or 4x wide columns at speed. So we are one week into this Boss's routine and you can see from the below video the horizontal scaling is implented ( vertical will be in the next update ) . We are scaling from 1x to 4x in the video below in 74 steps for testing . The column distributions are always a bit painfull to do - thankfully they are all worked out now. This is the third scaler I have built and the goal was with this one to make it really flexible for use in other projects also, sometimes when you optimise something to the last degree all the flexibility gets taken out of it. Currenty scaling at 12-25 FPS update here, I had some rules against some optimisations which I would use and some I wouldn't , thankfully we are a bit ahead of the Arcades animation frame rate here still and I may yet find optimisations that fit within the scope. We have vertical scaling and sprite spikes to add yet so Im hoping i can find a few more optimisations to offset things when they are implemented also. In a scale frame update we are processing close to 42000 pixels in ram before using DMA to send to VRAM . Using a 41x16 (656 tile scale buffer) - single buffered for now due to its size in VRAM. So thats nearly 21k in tiles ! I had to re-organise ram a bit to support a buffer of that size for the stage. The scaling function is written in 68k assembly , with a little C code handling the Vertical interupt code ( so the game logic can actually run & DMA updates etc ) . The DMA routines are in assembly also and customised for large chunk size ( big blocks of tiles ) which suits the scaler. I had some race conditions to sort out where the cpu was faster than DMA (sending tiles from RAM to VRAM ) and in some cases where it wasn't so it had to be balanced. We may be able to add more detail into the top and bottom of the background yet but its low priority for now until all the other bits are in !! #SGDK #SegaMegadrive #Genesis #Parodius

Shannon Birt

25,470 Aufrufe • vor 4 Monaten

*** Parodius Update - LAZERS !! *** How many sprites do we have to use on the Sega Genesis to make 4 x 160 pixel wide lazers ?? 10 ? 20 ? ZERO !! Which is really great as when the options overlap all with Lazers using sprites would have lead to sprite severe overload / dropout otherwise. So yes we have some raster trickery going on . I think this might take the cake for the most exotic effect Ive added just for a power up type haha. Breaking down the effect. 1.) Lazer tile rows ( the tile rows the lazers are currently on ) are copied to an offscreen area of the plane . I used the DMA VRAM to VRAM copy mode for this. You can see these offscreen rows just above the Game Videos window in the Plane A tilemap view. 2.) Then a solid block of Lazer colored tiles is drawn at the position of the Lazer horizontally in the offscreen buffer we just copied too - these are 8x8 tiles. 3.) Then onscreen when as the display is being drawn we change to the Lazers row at the correct pixel line offset for exactly 1 scanline then change back to the normal screens next row. I'm using the Horizontal interupt system developed in SOTA for handling the interupts for this. The technique used has been done before on the NES ( Salamander tech demo ) , as usual some of the best techniques come from the 8 bit systems , still it presented challenges getting it working on the MD. These irregular spaced interupts on the Genesis are a little bit of a problem too . All the height sorting has to be done on the frame before. Whats very interesting about the VRAM to VRAM copy DMA (Copy DMA) is it runs asynchronous to the CPU. Normally ROM/RAM to VRAM write DMA (Write DMA) halts the CPU during the send operation but with a Copy DMA I can pipeline one Copy DMA setup while the previous one is copying still . So even though the Copy DMA is 1/2 the speed of a Write DMA with the pipelining and no stalling its probably on par or better in some cases , where a copy makes sense to use. Theres still need some fine tuning , might make smaller lazers with more breaks etc. The Lazers can be full screen width , or narrow as we want so bit of fine tuning here to come. Pyron Vector Orbitex #Parodius #SegaMegadrive #SegaGenesis #SGDK

Shannon Birt

16,162 Aufrufe • vor 9 Monaten

*** Mega Parodius Sega Megadrive Update *** Lately I've been having some fun seeing how far we can push the Parodius game engine . This is not arcade accurate - just for testing, decreased bullet timers and upped the bullet count to see what would happen re cpu usage when things are made a lot busier ! Maybe something like this could be insane mode in the options etc. Since last update we are a lot more optimised under the hood . The C based sprite engine, particularly visibility checking was speedup , overall 25 % faster. Then re-wrote the sprite engine completely in 68k assembly , 30% faster again. It took about 3 days and 1500 lines of assembly , thankfully the gains were worth it. All these gains will be back ported to S.O.T.A also as its using the same sprite engine. Usage is around 19% of cpu per frame with a full sprite load - 33 % cpu left in the busiest frame currently . Parodius is using a write the sprite list every frame type engine , so priority and meta-sprite objects can be handled with ease albiet its still a bit slower than static allocation sprite engines such as the one in lufthoheit but this is a bit easier to code for in the long run. All collision checks are been done , we are using a spatial grid system to get the collision checks done faster than a brute force approach . To get to maximum sprite count destruction is disabled in the video. We hit 80 sprites onscreen in this sequence , the sprite counter is one the Left side. We use about 16 sprites in the top hud and water line , about 21 for player attacks / missiles / shots / options . Up to 35 bullets + enemies . No lazer usage here as the Lazers use zero sprites thanks to the raster tricks , this video is all about the sprites ! Improved the water line when the Catboss is active , as he is Sprites + Forground we are doing some tile rotation tricks eg bit scrolling to give the impression of parrallax at that point . Vector Orbitex has updated the stage 1 music again and has made things even higher quality , hes mixed pcm and fm channels together to create higher quality orchestral hits for example . Pyron has started converting assets from stage 2/3 , some amazing work there . Hes well ahead of me at present which is a good thing. Still lots of incomplete animations missing logic etc , its slow going with RL getting in the way haha and 2 other projects !! Still its fun !! #SGDK #SegaMegadrive #SegaGenesis #Parodius

Shannon Birt

16,084 Aufrufe • vor 5 Monaten

** SEGA GENESIS - LUFTHOHEIT - Tunnel Stage Preview ** We are pleased to show an early preview of part of our Tunnel/ Vortex Stage. Big shout out to Carsten666 for his gorgeous Graphics, CYBERDEOUS - Crouzet Laurent for the amazingly well matched Audio to this level, Stephane for creating SGDK in the first place and being very supportive with new features in SGDK also. Technically this stage was a bit of a challenge, some notes below re this. To drive the rolling texture of the background - 40 horizontal interrupts are used, executing 120 scanlines of color change, changing 5 colors per line = 600 color changes per frame. Variable spaced interrupts are used for expansion / compression effect. Four stages of brightness used for every texture / pattern , darkest in the center of screen , brightest top & bottom. New colors created by alternating two similar colors at 60 hz, for seams between brightness regions to increase the blending between regions. Co-operative Multi-threading system used to reclaim huge amounts of CPU within the color change interrupts. For example all rolling Cannon & Cannon bullets and Debris are moved using this technique - up to 25% of total CPU can be reclaimed ( its normally wasted polling for rhs/hblank ). Heatseeking missiles, these need trajectory's recalculated frequently and doing that at speed can be tricky - lots of missiles launched at Mid video and its the heaviest CPU load in the demo ( these are not using the Multi-threading technique yet ). Variable rate collision checking, as bullets gets very close to player the checking is done at 60 fps, as they get further away the checking drops off rapidly - this saves cpu. Runs 60 FPS at all times, works on real HW also but captured on emulator as my phone doesnt take 60hz video without getting out of sync. Intro & Foreground effects are coming, currently no foreground is present as its not quite baked enough yet, we have some cool things we will do with the extra plane yet. Lots of good stuff to come !! #SGDK #SegaGenesis #SegaMegadrive

Shannon Birt

23,873 Aufrufe • vor 1 Jahr

** Mega Parodius Update ** The team have been busy over last couple of weeks , implementing more of the games engine. WIP since last update : White Bell power up ( this is the text attack ) Blue Bell power up ( full screen explosion ) Catboss & animating Trees Updated Lazers to work on the BGB layer ( Plane A updated to 64x64 tilemap ) . Pyron has been doing excellent work on Blue bell Explosion, Whitebell power up text gfx - the slogans are great !! Arcade quality tree animations have been added. Feeding me a lot of videos so we can replicate the arcade port more accurately. Vector Orbitex has updated the music to mark IV for stage 1 making it smaller yet again , he's also added the Orchestra Hit in , potentially more samples can be added back in now also as the song now is a miniscule 57 kb. I keep telling him its 2025 - not 1990 for rom sizes haha , a professional is always a professional though !! The Blue Bell power up uses the static large sprite class I made for SOTA where it supports unlimited amount of sprites per object and detects all the reverses / flips & uses the same tile pointers where it can and crunches it down into single sprite object. We use up to 40 sprites in the Explosion but only 147 tiles needed in vram thanks to clever use of mirroring. The Catboss is easily the hardest enemy in the level for a few reasons - we also had to free up Plane A so the boss could shift upwards onscreen, so lazer effects were shifted to Plane B. The bit that caused me the most issues was when he sits in the water line between the two islands. He is quite wide and also has overlapping palettes and animating parts , to do it solely with sprites would have lead to severe dropout at times. At the waterline we have to simulate 3 background planes and sprites at that point and we only have 2 background planes. Luckily the MD sprite engine is very flexible and we were able to recreate the arcade look at this point with some sprite trickery, the water-line is now sprites . So we use Plane A + sprites to recreate him and use a lot of plane animation to reduce the amount of sprites needed. For example the face, the tail the propeller are all plane A animations . I analysed the SNES/PCE versions and we use less sprites than those versions for him so that will help reduce the chance of sprite dropout when attacking. The Catboss is only about 1/2 done , all damage states, the onboard penguin factory, bullets from Cannons yet to added etc. He wraps around at the end of the vid as theres no destruction routine in for him yet . No extra enemies in at this stage , tackling the hard parts first etc. We took the arcade GFX for the Trees that sway around under the Catboss, all the animations are in. There were some DMA bandwidth issues originally I had to sort out as the Catboss has several animating parts + swaying Trees was leading to overload so after some load balancing it all is playing nicely !! We still have loads of stuff to add , collisions are not in - normal enemy waves etc but yeah a lot of future issues were sorting out just getting this far. So the team is very happy with the progress !! #SGDK #Parodius #SegaGenesis #SegaMegadrive #indiegame

Shannon Birt

19,194 Aufrufe • vor 7 Monaten