; Renders a frame of animation ; ; The render function is the point of committment -- most of the APIs that set sprites and ; update coordinates are lazy; they simply save their values and set a dirty flag in the ; DirtyBits word. ; ; This function examines the dirty bits and actually performs the work to update the code field ; and internal data structure to properly render the play field. Then the update pipeline is ; executed. ; ; Everything is composited into the tiles in the playfield and then the screen is rendered in ; a single pass. ; ; TODO -- actually check the dirty bits and be selective on what gets updated. For example, if ; only the Y position changes, then we should only need to set new values on the ; virtual lines that were brought on screen. If the X position only changes by one ; byte, then we may have to change the CODE_ENTRY values or restore/set new OPCODE ; values, but not both. ; It's important to do _ApplyBG0YPos first because it calculates the value of StartY % 208 which is ; used in all of the other loops _Render jsr _DoTimers ; Run any pending timer tasks stz SpriteRemovedFlag ; If we remove a sprite, then we need to flag a rebuild for the next frame jsr _ApplyBG0YPos ; Set stack addresses for the virtual lines to the physical screen ; jsr _ApplyBG1YPos ; _ApplyBG0Xpos need to be split because we have to set the offsets, then draw in any updated tiles, and ; finally patch out the code field. Right now, the BRA operand is getting overwritten by tile data. jsr _ApplyBG0XPosPre ; jsr _ApplyBG1XPosPre jsr _RenderSprites ; Once the BG0 X and Y positions are committed, update sprite data jsr _UpdateBG0TileMap ; and the tile maps. These subroutines build up a list of tiles ; jsr _UpdateBG1TileMap ; that need to be updated in the code field jsr _ApplyTilesFast ; This function actually draws the new tiles into the code field jsr _ApplyBG0XPos ; Patch the code field instructions with exit BRA opcode ; jsr _ApplyBG1XPos ; Update the direct page value based on the horizontal position ; The code fields are locked in now and ready to be rendered ; jsr _ShadowOff ; Shadowing is turned off. Render all of the scan lines that need a second pass. One ; optimization that can be done here is that the lines can be rendered in any order ; since it is not shown on-screen yet. ; ldx #0 ; Blit the full virtual buffer to the screen ; ldy #8 ; jsr _BltRange ; Turn shadowing back on ; jsr _ShadowOn ; Now render all of the remaining lines in top-to-bottom (or bottom-to-top) order ; lda ScreenY0 ; pass the address of the first line of the overlay ; clc ; adc #0 ; asl ; tax ; lda ScreenAddr,x ; clc ; adc ScreenX0 ; jsl Overlay ldx #0 ; Blit the full virtual buffer to the screen ldy ScreenHeight jsr _BltRange ; ldx #0 ; ldy ScreenHeight ; jsr _BltSCB lda StartYMod208 ; Restore the fields back to their original state ldx ScreenHeight jsr _RestoreBG0Opcodes lda StartY sta OldStartY lda StartX sta OldStartX lda BG1StartY sta OldBG1StartY lda BG1StartX sta OldBG1StartX stz DirtyBits stz LastRender ; Mark that a full render was just performed lda SpriteRemovedFlag ; If any sprite was removed, set the rebuild flag beq :no_removal lda #DIRTY_BIT_SPRITE_ARRAY sta DirtyBits :no_removal rts ; The _ApplyTilesFast is the same as _ApplyTiles, but we use the _RenderTileFast subroutine _ApplyTilesFast ldx DirtyTileCount tdc clc adc #$100 ; move to the next page tcd stx DP2_DIRTY_TILE_COUNT ; Cache the dirty tile count jsr _PopDirtyTilesFast tdc ; Move back to the original direct page sec sbc #$100 tcd stz DirtyTileCount ; Reset the dirty tile count rts ; The _ApplyTiles function is responsible for rendering all of the dirty tiles into the code ; field. In this function we switch to the second direct page which holds the temporary ; working buffers for tile rendering. ; _ApplyTiles tdc clc adc #$100 ; move to the next page tcd bra :begin :loop ; Retrieve the offset of the next dirty Tile Store items in the X-register jsr _PopDirtyTile2 ; Call the generic dispatch with the Tile Store record pointer at by the X-register. phb ; jsr _RenderTile2 plb ; Loop again until the list of dirty tiles is empty :begin ldy DirtyTileCount bne :loop tdc ; Move back to the original direct page sec sbc #$100 tcd rts ; This is a specialized render function that only updates the dirty tiles *and* draws them ; directly onto the SHR graphics buffer. The playfield is not used at all. In some way, this ; ignores almost all of the capabilities of GTE, but it does provide a convenient way to use ; the sprite subsystem + tile attributes for single-screen games which should be able to run ; close to 60 fps. ; ; In this renderer, we assume that there is no scrolling, so no need to update any information about ; the BG0/BG1 positions _RenderDirty lda LastRender ; If the full renderer was last called, we assume that bne :norecalc ; the scroll positions have likely changed, so recalculate jsr _RecalcTileScreenAddrs ; them to make sure sprites draw at the correct screen address ; jsr _ClearSpritesFromCodeField ; Restore the tiles to their non-sprite versions :norecalc ; jsr _RenderSprites ; jsr _ApplyDirtyTiles lda #1 sta LastRender rts _ApplyDirtyTiles bra :begin :loop ; Retrieve the offset of the next dirty Tile Store items in the Y-register jsr _PopDirtyTile2 ; Call the generic dispatch with the Tile Store record pointer at by the Y-register. phb jsr _RenderDirtyTile plb ; Loop again until the list of dirty tiles is empty :begin ldy DirtyTileCount bne :loop rts ; Only render solid tiles and sprites _RenderDirtyTile lda TileStore+TS_SPRITE_FLAG,y beq NoSpritesDirty ; This is faster if there are no sprites ; TODO: handle sprite drawing ; The rest of this function handles that non-sprite blit, which is super fast since it blits directly from the ; tile data store to the graphics screen with no masking. The only extra work is selecting a blit function ; based on the tile flip flags. ; ; B is set to Bank 01 ; Y is set to the top-left address of the tile in SHR screen ; A is set to the address of the tile data NoSpritesDirty ; lda TileStore+TS_DIRTY_TILE_DISP,y ; stal :nsd+1 ldx TileStore+TS_SCREEN_ADDR,y ; Get the on-screen address of this tile lda TileStore+TS_TILE_ADDR,y ; load the address of this tile's data (pre-calculated) plb ; set the code field bank :nsd jmp $0000 ; Use some temporary space for the spriteIdx array (maximum of 4 entries) stkSave equ tmp9 screenAddr equ tmp10 tileAddr equ tmp11 spriteIdx equ tmp12 ; If there are two or more sprites at a tile, we can still be fast, but need to do extra work because ; the VBUFF values need to be read from the direct page. Thus, the direct page cannot be mapped onto ; the graphics screen. We use the stack instead, but have to do extra work to save and restore the ; stack value. FourSpritesDirty ThreeSpritesDirty TwoSpritesDirty sta tileAddr stx screenAddr plb tsc sta stkSave ; Save the stack on the direct page sei clc ldy tileAddr lda screenAddr ; Saved in direct page locations tcs _R0W1 lda tiledata+{0*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{0*SPRITE_PLANE_SPAN},x oral spritedata+{0*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{0*SPRITE_PLANE_SPAN},x oral spritedata+{0*SPRITE_PLANE_SPAN},x sta $00,s lda tiledata+{0*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{0*SPRITE_PLANE_SPAN}+2,x oral spritedata+{0*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{0*SPRITE_PLANE_SPAN}+2,x oral spritedata+{0*SPRITE_PLANE_SPAN}+2,x sta $02,s lda tiledata+{1*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{1*SPRITE_PLANE_SPAN},x oral spritedata+{1*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{1*SPRITE_PLANE_SPAN},x oral spritedata+{1*SPRITE_PLANE_SPAN},x sta $A0,s lda tiledata+{1*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{1*SPRITE_PLANE_SPAN}+2,x oral spritedata+{1*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{1*SPRITE_PLANE_SPAN}+2,x oral spritedata+{1*SPRITE_PLANE_SPAN}+2,x sta $A2,s tsc adc #320 tcs lda tiledata+{2*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{2*SPRITE_PLANE_SPAN},x oral spritedata+{2*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{2*SPRITE_PLANE_SPAN},x oral spritedata+{2*SPRITE_PLANE_SPAN},x sta $00,s lda tiledata+{2*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{2*SPRITE_PLANE_SPAN}+2,x oral spritedata+{2*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{2*SPRITE_PLANE_SPAN}+2,x oral spritedata+{2*SPRITE_PLANE_SPAN}+2,x sta $02,s lda tiledata+{3*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{3*SPRITE_PLANE_SPAN},x oral spritedata+{3*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{3*SPRITE_PLANE_SPAN},x oral spritedata+{3*SPRITE_PLANE_SPAN},x sta $A0,s lda tiledata+{3*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{3*SPRITE_PLANE_SPAN}+2,x oral spritedata+{3*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{3*SPRITE_PLANE_SPAN}+2,x oral spritedata+{3*SPRITE_PLANE_SPAN}+2,x sta $A2,s tsc adc #320 tcs lda tiledata+{4*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{4*SPRITE_PLANE_SPAN},x oral spritedata+{4*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{4*SPRITE_PLANE_SPAN},x oral spritedata+{4*SPRITE_PLANE_SPAN},x sta $00,s lda tiledata+{4*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{4*SPRITE_PLANE_SPAN}+2,x oral spritedata+{4*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{4*SPRITE_PLANE_SPAN}+2,x oral spritedata+{4*SPRITE_PLANE_SPAN}+2,x sta $02,s lda tiledata+{5*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{5*SPRITE_PLANE_SPAN},x oral spritedata+{5*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{5*SPRITE_PLANE_SPAN},x oral spritedata+{5*SPRITE_PLANE_SPAN},x sta $A0,s lda tiledata+{5*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{5*SPRITE_PLANE_SPAN}+2,x oral spritedata+{5*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{5*SPRITE_PLANE_SPAN}+2,x oral spritedata+{5*SPRITE_PLANE_SPAN}+2,x sta $A2,s tsc adc #320 tcs lda tiledata+{6*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{6*SPRITE_PLANE_SPAN},x oral spritedata+{6*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{6*SPRITE_PLANE_SPAN},x oral spritedata+{6*SPRITE_PLANE_SPAN},x sta $00,s lda tiledata+{6*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{6*SPRITE_PLANE_SPAN}+2,x oral spritedata+{6*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{6*SPRITE_PLANE_SPAN}+2,x oral spritedata+{6*SPRITE_PLANE_SPAN}+2,x sta $02,s lda tiledata+{7*TILE_DATA_SPAN},y ldx spriteIdx+2 andl spritemask+{7*SPRITE_PLANE_SPAN},x oral spritedata+{7*SPRITE_PLANE_SPAN},x ldx spriteIdx andl spritemask+{7*SPRITE_PLANE_SPAN},x oral spritedata+{7*SPRITE_PLANE_SPAN},x sta $A0,s lda tiledata+{7*TILE_DATA_SPAN}+2,y ldx spriteIdx+2 andl spritemask+{7*SPRITE_PLANE_SPAN}+2,x oral spritedata+{7*SPRITE_PLANE_SPAN}+2,x ldx spriteIdx andl spritemask+{7*SPRITE_PLANE_SPAN}+2,x oral spritedata+{7*SPRITE_PLANE_SPAN}+2,x sta $A2,s _R0W0 lda stkSave tcs cli rts ; There is only one sprite at this tile, so do a fast blit that directly combines a tile with a single ; sprite and renders directly to the screen ; ; NOTE: Expect X-register to already have been set to the correct VBUFF address OneSpriteDirty ldy tileAddr ; load the address of this tile's data lda screenAddr ; Get the on-screen address of this tile plb phd sei clc tcd _R0W1 lda tiledata+{0*TILE_DATA_SPAN},y andl spritemask+{0*SPRITE_PLANE_SPAN},x oral spritedata+{0*SPRITE_PLANE_SPAN},x sta $00 lda tiledata+{0*TILE_DATA_SPAN}+2,y andl spritemask+{0*SPRITE_PLANE_SPAN}+2,x oral spritedata+{0*SPRITE_PLANE_SPAN}+2,x sta $02 lda tiledata+{1*TILE_DATA_SPAN},y andl spritemask+{1*SPRITE_PLANE_SPAN},x oral spritedata+{1*SPRITE_PLANE_SPAN},x sta $A0 lda tiledata+{1*TILE_DATA_SPAN}+2,y andl spritemask+{1*SPRITE_PLANE_SPAN}+2,x oral spritedata+{1*SPRITE_PLANE_SPAN}+2,x sta $A2 tdc adc #320 tcd lda tiledata+{2*TILE_DATA_SPAN},y andl spritemask+{2*SPRITE_PLANE_SPAN},x oral spritedata+{2*SPRITE_PLANE_SPAN},x sta $00 lda tiledata+{2*TILE_DATA_SPAN}+2,y andl spritemask+{2*SPRITE_PLANE_SPAN}+2,x oral spritedata+{2*SPRITE_PLANE_SPAN}+2,x sta $02 lda tiledata+{3*TILE_DATA_SPAN},y andl spritemask+{3*SPRITE_PLANE_SPAN},x oral spritedata+{3*SPRITE_PLANE_SPAN},x sta $A0 lda tiledata+{3*TILE_DATA_SPAN}+2,y andl spritemask+{3*SPRITE_PLANE_SPAN}+2,x oral spritedata+{3*SPRITE_PLANE_SPAN}+2,x sta $A2 tdc adc #320 tcd lda tiledata+{4*TILE_DATA_SPAN},y andl spritemask+{4*SPRITE_PLANE_SPAN},x oral spritedata+{4*SPRITE_PLANE_SPAN},x sta $00 lda tiledata+{4*TILE_DATA_SPAN}+2,y andl spritemask+{4*SPRITE_PLANE_SPAN}+2,x oral spritedata+{4*SPRITE_PLANE_SPAN}+2,x sta $02 lda tiledata+{5*TILE_DATA_SPAN},y andl spritemask+{5*SPRITE_PLANE_SPAN},x oral spritedata+{5*SPRITE_PLANE_SPAN},x sta $A0 lda tiledata+{5*TILE_DATA_SPAN}+2,y andl spritemask+{5*SPRITE_PLANE_SPAN}+2,x oral spritedata+{5*SPRITE_PLANE_SPAN}+2,x sta $A2 tdc adc #320 tcd lda tiledata+{6*TILE_DATA_SPAN},y andl spritemask+{6*SPRITE_PLANE_SPAN},x oral spritedata+{6*SPRITE_PLANE_SPAN},x sta $00 lda tiledata+{6*TILE_DATA_SPAN}+2,y andl spritemask+{6*SPRITE_PLANE_SPAN}+2,x oral spritedata+{6*SPRITE_PLANE_SPAN}+2,x sta $02 lda tiledata+{7*TILE_DATA_SPAN},y andl spritemask+{7*SPRITE_PLANE_SPAN},x oral spritedata+{7*SPRITE_PLANE_SPAN},x sta $A0 lda tiledata+{7*TILE_DATA_SPAN}+2,y andl spritemask+{7*SPRITE_PLANE_SPAN}+2,x oral spritedata+{7*SPRITE_PLANE_SPAN}+2,x sta $A2 _R0W0 cli pld rts