CydandClaude Fable 5
db7745fcd0
Un-ignored: the dev drive is the ground truth the restoration and emulator work constantly reference (DPL3/LIBDPL + VRENDER i860 renderer source, BT/RP live+dev game trees, VGL_LABS pod boot, scene/audio content). Kept in-repo for the pod-owner community. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
64 lines
1.7 KiB
Plaintext
64 lines
1.7 KiB
Plaintext
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To render a scene using the dma engine -
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void renderScene()
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{
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start_up_frame();
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tile=0;
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scan_convert(tile, 0);
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/* now wait for 1 interrupt from DMA engine */
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tile++;
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while (tile < tiles_in_frame) {
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scan_convert(tile, 1);
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/*
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now wait for 2 interrupts from DMA engine, from scan-converter
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and from end-of-texture
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*/
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VRAMwritetoFrameStore(tile);
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tile++;
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}
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scan_convert ( -1, 1 );
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/*
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again wait for 2 interrupts from DMA engine, 1 of which
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appears real soon since there are no triangles in the NULL image!
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*/
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VRAMwritetoFrameStore(tile);
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/*
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and we know that the last tile is at the bottom-right
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of the screen, so we can flip frames at any point from here
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*/
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}
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The sync point is the end of texture() AND end of scan_convert().
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How do i organise this sync? The tranny needs to see 2 events (is there a
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race condition potentially in the event hardware?) before walking to the
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next tile. The code for 'texture tile' needs to do the end-of-frame code
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up to and including the VRAMwrite(), then GOTO scan-convert (next tile).
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The trick is to move the end-of-frame code to the BEGINNING of each tile.
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So tile 0 doesnt execute any end-of-frame code (achieved via a jump). All
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other tiles begin by executing the end-of-frame code for the previous
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tile. The end-of-frame code consists of
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computing a 24-bit pixel from intrinsic
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moving all variables into eof area
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perspective divide
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put texture address into bits 0..31
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VRAMwrite (for texture lookup)
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configure EMC's to new tileXY
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clear out scan-converting area
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start scan-converting polygons
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