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