******************************************************************** * * Landscape_Calc * * Calculation routines for 'landscape' (68K) * * assemble with: * phxass Landscape_Calc.s to Landscape_Calc.o smallcode * * link with smalldata and smallcode enabled * * © 1997 HAAGE&PARTNER Computer GmbH * ******************************************************************** include landscape.i include debug.i DB_DEBUG set DB_OFF ;// XDEF / XREF xdef CreateLandscape xref PrepareFlight xref _PowerPCBase xref ChunkyBuffer xref MapSize xref MapSizeExp xref MapMem xref MapMemEnd xref MapScale xref browntab xref Code xref H xref Iterations xref Variation xref Water xref Shadow xref LightDir xref LightAngle xref RanCount xref Highest xref Lowest xref tantab xref AreaWidth xref AreaHeight xref BitmapWidth xref MapDim xref MapHeight ;;/ mc68020 fpu section "Landscape_Code_Calc",code * landscape generator ;// CreateLandscape (creates the landscape) ****************************************************************************** * * CreateLandscape * * creates the landscape * ****************************************************************************** CreateLandscape movem.l d2-d7,-(sp) fmovem.x fp0-fp2,-(sp) bsr SetRNDModeRZ ;enable rounding mode RZ move.l d0,d7 ;save old FPCR move.l MapMem,a0 ;-> map space lea browntab,a1 ;-> math table moveq #0,d0 moveq #0,d1 moveq #0,d2 moveq #0,d3 move.b MapSizeExp,d0 ;map size exponential move.b Iterations,d1 ;iterations for subdivision move.b H,d2 ;fractal parameter move.b RanCount,d3 bsr BuildLandscape ;build landscape move.l MapMem,a0 ;-> map space move.l MapSize,d0 ;map size moveq #0,d1 move.b Water,d1 ;water area bsr ScaleLandscape ;scale landscape move.l MapMem,a0 ;-> map space move.l MapSize,d0 ;map size moveq #0,d1 moveq #0,d2 move.b Variation,d1 ;color variation move.b RanCount,d2 bsr CreateColors ;define colors tst.b Shadow ;Shadow enabled? beq.b .noshadow ;no -> jump move.l MapMem,a0 ;-> map space move.l MapSize,d0 ;map size lea tantab,a1 ;tangens table moveq #0,d1 moveq #0,d2 move.b LightDir,d1 ;light direction move.b LightAngle,d2 ;light angle bsr CreateShadow ;create shadow .noshadow move.l d7,d0 ;get FPCR bsr RestoreRNDMode ;restore FPCR fmovem.x (sp)+,fp0-fp2 movem.l (sp)+,d2-d7 rts ;;/ ;// BuildLandscape (creates the landscape using a fractal algorithm) ****************************************************************************** * * BuildLandscape (a0,a1,d0,d1,d2,d3,d4) * * creates the landscape using a fractal algorithm * height = average_height + random * 0.5^(Iterations*H) * * In: a0 -> map memory * a1 -> math table for fractal computation * d0 = map border size (exp.) * d1 = number of iterations for subdivision * d2 = H (fractal parameter) * d3 = number of uniform random numbers for one normal random number * ****************************************************************************** BuildLandscape movem.l d2-d7/a2-a6,-(sp) move.l d3,d4 move.l d2,d3 move.l d1,d5 lsl.l #5,d5 ;calc offset into math table add.l d5,a1 ;a1 -> current entry add.l d3,d3 ;calc offset for H parameter add.l d3,a1 ;a1 -> 0.5^(It.*H)<<14 move.l d4,a6 move.l d0,d5 ;calculate number of iterations sub.l d1,d5 subq.l #1,d5 ;d5 = iteration loop count moveq #1,d6 ;calc map border size lsl.l d0,d6 move.l d6,d0 ;d0 = map border size moveq #1,d6 ;calc matrix loop counter moveq #1,d7 lsl.l d1,d6 ;d6 = vertical loop counter lsl.l d1,d7 ;d7 = horizontal loop counter move.l d6,a2 move.l d5,d6 move.l d7,a3 move.l d0,d4 ;calc map step value lsr.l d1,d4 add.l d4,d4 ;d4 = horizontal step value move.l d4,d2 mulu.l d0,d2 ;d2 = vertical step value move.l d0,d5 ;calc map mask values add.l d0,d0 mulu.l d0,d5 subq.l #1,d0 ;d0 = horizontal map mask subq.l #1,d5 ;d5 = vertical map mask .loop move.l d6,a5 ;save iteration counter move.l a2,d6 ;restore vertical loop counter subq #1,d6 moveq #0,d1 ;reset vertical position .loop2 move.l a3,d7 ;restore horizontal loop counter subq #1,d7 moveq #0,d3 ;reset horizontal position .loop3 exg a6,d6 bsr SetCenter ;calc height of center field exg a6,d6 add.l d4,d3 ;increase horizontal position dbra d7,.loop3 add.l d2,d1 ;increase vertical position dbra d6,.loop2 lea 32(a1),a1 ;next math table entry move.l a2,d6 ;restore vertical loop counter subq #1,d6 moveq #0,d1 ;reset vertical position .loop4 move.l a3,d7 ;restore horizontal loop counter subq #1,d7 moveq #0,d3 ;reset horizontal position .loop5 exg a6,d6 bsr SetUpper ;calc height of upper field bsr SetLeft ;calc height of left field exg a6,d6 add.l d4,d3 ;increase horizontal position dbra d7,.loop5 add.l d2,d1 ;increase vertical position dbra d6,.loop4 lea 32(a1),a1 ;next math table entry add.l a3,a3 ;double horizontal counter add.l a2,a2 ;double vertical counter lsr.l #1,d4 ;halve horizontal step value lsr.l #1,d2 ;halve vertical step value move.l a5,d6 ;restore iteration counter dbra d6,.loop ;next iteration movem.l (sp)+,d2-d7/a2-a6 rts ;;/ ;// SetCenter (sets the height of the center of a specific square) ****************************************************************************** * * SetCenter (a0,a1,d0,d1,d2,d3,d4,d5,d6) * * sets the height of the center of a specific square * * In: a0 -> map memory * a1 -> fractal exponent * d0 = horizontal map mask * d1 = vertical offset of the top border of the square * d2 = differential vertical offset * d3 = horizontal offset of the left border of the square * d4 = differential horizontal offset * d5 = vertical map mask * d6 = number of uniform random numbers for one normal random number * ****************************************************************************** SetCenter movem.l d0-a2,-(sp) move.l d6,a2 moveq #0,d6 move.l d3,d7 add.l d1,d7 move 0(a0,d7.l),d7 ;read left top height ext.l d7 add.l d7,d6 ;add to d6 move.l d3,d7 add.l d4,d7 and.l d0,d7 add.l d1,d7 move 0(a0,d7.l),d7 ;read right top height ext.l d7 add.l d7,d6 ;add to d6 move.l d1,d7 add.l d2,d7 and.l d5,d7 add.l d3,d7 move 0(a0,d7.l),d7 ;read left bottom height ext.l d7 add.l d7,d6 ;add to d6 move.l d3,d7 add.l d4,d7 and.l d0,d7 move.l d1,d0 add.l d2,d0 and.l d5,d0 add.l d0,d7 move 0(a0,d7.l),d7 ;read right bottom height ext.l d7 add.l d7,d6 ;add to d6 asr.l #2,d6 ;calc average height move.l d3,d7 add.l d1,d7 lsr.l #1,d4 ;halve square width lsr.l #1,d2 ;halve square height add.l d4,d7 add.l d2,d7 ;calc offset into center add.l d7,a0 ;a0 -> center field move.l a2,d7 ;get random number count subq #1,d7 moveq #0,d4 ;init sum value .loop bsr URN30 ;get random value sub.l #$3fffffff,d0 ;scale random value asr.l #4,d0 add.l d0,d4 ;add to sum value dbra d7,.loop swap d4 move (a1),d0 ;read fractal exponent muls d0,d4 ;multiply with random value moveq #12,d0 ;scale result asr.l d0,d4 add d6,d4 ;add to average height move Highest,d0 ;check if highest point cmp d0,d4 ble.b .cont move d4,Highest ;yes -> replace .cont move Lowest,d0 ;check if lowest point cmp d0,d4 bge.b .cont2 move d4,Lowest ;yes -> replace .cont2 move d4,(a0) ;store height into center field movem.l (sp)+,d0-a2 rts ;;/ ;// SetUpper (sets the height of the upper point of a specific square) ****************************************************************************** * * SetUpper (a0,a1,d0,d1,d2,d3,d4,d5,d6) * * sets the height of the upper point of a specific square * * In: a0 -> map memory * a1 -> fractal exponent * d0 = horizontal map mask * d1 = vertical offset of the top border of the square * d2 = differential vertical offset * d3 = horizontal offset of the left border of the square * d4 = differential horizontal offset * d5 = vertical map mask * d6 = number of uniform random numbers for one normal random number * ****************************************************************************** SetUpper movem.l d0-a2,-(sp) move.l d6,a2 moveq #0,d6 move.l d3,d7 add.l d1,d7 move 0(a0,d7.l),d7 ;read left top height ext.l d7 add.l d7,d6 ;add to d6 move.l d3,d7 add.l d4,d7 and.l d0,d7 add.l d1,d7 move 0(a0,d7.l),d7 ;read right top height ext.l d7 add.l d7,d6 ;add to d6 lsr.l #1,d2 ;halve square width lsr.l #1,d4 ;halve square height move.l d3,d7 add.l d4,d7 move.l d1,d0 add.l d2,d0 and.l d5,d0 add.l d0,d7 move 0(a0,d7.l),d7 ;read center bottom height ext.l d7 add.l d7,d6 ;add to d6 move.l d3,d7 add.l d4,d7 move.l d1,d0 sub.l d2,d0 and.l d5,d0 add.l d0,d7 move 0(a0,d7.l),d7 ;read center top height ext.l d7 add.l d7,d6 ;add to d6 asr.l #2,d6 ;calc average height move.l d3,d7 add.l d4,d7 add.l d1,d7 ;calc offset to upper field add.l d7,a0 ;a0 -> upper field move.l a2,d7 subq #1,d7 moveq #0,d4 .loop bsr URN30 ;same as 'SetCenter' sub.l #$3fffffff,d0 asr.l #4,d0 add.l d0,d4 dbra d7,.loop swap d4 move (a1),d0 muls d0,d4 moveq #12,d0 asr.l d0,d4 add d6,d4 move Highest,d0 cmp d0,d4 ble.b .cont move d4,Highest .cont move Lowest,d0 cmp d0,d4 bge.b .cont2 move d4,Lowest .cont2 move d4,(a0) ;store height into upper field movem.l (sp)+,d0-a2 rts ;;/ ;// SetLeft (sets the height of the left point of a specific square) ****************************************************************************** * * SetLeft (a0,a1,d0,d1,d2,d3,d4,d5,d6) * * sets the height of the left point of a specific square * * In: a0 -> map memory * a1 -> fractal exponent * d0 = horizontal map mask * d1 = vertical offset of the top border of the square * d2 = differential vertical offset * d3 = horizontal offset of the left border of the square * d4 = differential horizontal offset * d5 = vertical map mask * d6 = number of uniform random numbers for one normal random number * ****************************************************************************** SetLeft movem.l d0-a2,-(sp) move.l d6,a2 moveq #0,d6 move.l d3,d7 add.l d1,d7 move 0(a0,d7.l),d7 ;read left top height ext.l d7 add.l d7,d6 ;add to d6 move.l d1,d7 add.l d2,d7 and.l d5,d7 add.l d3,d7 move 0(a0,d7.l),d7 ;read left bottom height ext.l d7 add.l d7,d6 ;add to d6 lsr.l #1,d4 ;halve square width lsr.l #1,d2 ;halve square height move.l d1,d7 add.l d2,d7 move.l d3,d5 add.l d4,d5 and.l d0,d5 add.l d5,d7 move 0(a0,d7.l),d7 ;read center right height ext.l d7 add.l d7,d6 ;add to d6 move.l d1,d7 add.l d2,d7 move.l d3,d5 sub.l d4,d5 and.l d0,d5 add.l d5,d7 move 0(a0,d7.l),d7 ;read center left height ext.l d7 add.l d7,d6 ;add to d6 asr.l #2,d6 ;calc average height move.l d1,d7 add.l d2,d7 add.l d3,d7 ;calc offset to left field add.l d7,a0 ;a0 -> left field move.l a2,d7 subq #1,d7 moveq #0,d4 .loop bsr URN30 ;same as 'SetCenter' sub.l #$3fffffff,d0 asr.l #4,d0 add.l d0,d4 dbra d7,.loop swap d4 move (a1),d0 muls d0,d4 moveq #12,d0 asr.l d0,d4 add d6,d4 move Highest,d0 cmp d0,d4 ble.b .cont move d4,Highest .cont move Lowest,d0 cmp d0,d4 bge.b .cont2 move d4,Lowest .cont2 move d4,(a0) ;store height into left field movem.l (sp)+,d0-a2 rts ;;/ ;// ScaleLandscape (scales the landscape) ****************************************************************************** * * ScaleLandscape (a0,d0,d1) * * scales the landscape * * In: a0 -> map memory * d0 = map border size * d1 = water area * ****************************************************************************** ScaleLandscape movem.l d2-d7,-(sp) move Highest,d2 ;read highest point move d2,d4 move Lowest,d3 ;read lowest point sub d3,d2 ;calc difference mulu d1,d2 divu #100,d2 add d2,d3 ;d3 = water NULL height sub d3,d4 ;d4 = height above water move d0,d6 move d0,d7 subq #1,d6 ;create loop counters subq #1,d7 move d7,d5 .loop move d5,d7 .loop2 move (a0),d0 ;read height sub d3,d0 ;shift up/down height muls #255,d0 ;scale height divs d4,d0 move d0,(a0)+ ;write new height dbra d7,.loop2 dbra d6,.loop movem.l (sp)+,d2-d7 rts ;;/ ;// CreateColors (defines the color values for each zone) ****************************************************************************** * * CreateColors (a0,d0,d1,d2) * * defines the color values for each zone * * In: a0 -> map memory * d0 = map border size * d1 = variation parameter (0 = standard) * d2 = number of uniform random numbers for one normal random number * ****************************************************************************** CreateColors movem.l d2-d7,-(sp) move.l d2,a1 move.l d0,d7 move.l d0,d2 mulu.l d2,d2 add.l d2,d2 ;d2 = map full size (in bytes) move.l d0,d4 add.l d4,d4 ;d4 = line size in bytes sub.l d4,d2 ;d2 = offset from last to first neg.l d2 ;line move.l d4,d3 ;d3 = offset from rightmost neg.l d3 ;to leftmost point subq #2,d7 ;create loop counters (one less move d7,d5 ;than usual) move.l d0,d6 subq #2,d6 exg d2,a1 .loop move d5,d7 .loop2 moveq #0,d0 add (a0),d0 ;calc average height of add 2(a0),d0 ;corresponding polygon add 0(a0,d4.l),d0 add 2(a0,d4.l),d0 asr #2,d0 ;d0 = average height bsr DefineColor ;assign color addq.l #2,a0 ;next height dbra d7,.loop2 moveq #0,d0 ;special case: polygon between add (a0),d0 ;rightmost and leftmost point add 2(a0),d0 add 0(a0,d4.l),d0 add 2(a0,d3.l),d0 asr #2,d0 bsr DefineColor addq.l #2,a0 dbra d6,.loop move d5,d7 .loop3 moveq #0,d0 ;special case: polygons between add (a0),d0 ;bottom line and top line add 2(a0),d0 add 0(a0,a1.l),d0 add 2(a0,a1.l),d0 asr #2,d0 bsr DefineColor addq.l #2,a0 dbra d7,.loop3 moveq #0,d0 ;special case: polygon between add (a0),d0 ;right-bottom point and left-top add 2(a0,d3.l),d0 ;point add 0(a0,a1.l),d0 add.l a1,d3 add 0(a0,d3.l),d0 asr #2,d0 bsr DefineColor movem.l (sp)+,d2-d7 rts ;;/ ;// DefineColor (calulates one color value) ****************************************************************************** * * DefineColor (a0,d0,d1,d2) * * defines the color values for each zone * * In: a0 -> 16 bit height element * d0 = average height of corresponding polygon * d1 = variation parameter * d2 = number of uniform random numbers for one normal random number * ****************************************************************************** DefineColor movem.l d1-d7/a1,-(sp) move (a0),d0 ;read height move d0,d4 move d0,d5 move d1,d6 tst d6 ;any variation wanted? beq .novariation ;no -> jump move d2,d7 ;number of random numbers subq #1,d7 sub.l a1,a1 ;init sum value .loop bsr URN30 ;calc random value sub.l #$3fffffff,d0 ;scale random value asr.l #4,d0 add.l d0,a1 ;add to sum dbra d7,.loop move.l a1,d0 swap d0 muls d0,d6 ;multiply with variation value asr.l #8,d6 ;scale result asr.l #6,d6 tst d5 ;polygon in water? ble.b .water1 ;yes -> jump add d6,d4 ;add variation to height bgt.b .cont ;still over water? -> jump moveq #1,d4 ;lowest point above water bra.b .novariation .cont cmp #255,d4 ;overflow? ble.b .novariation ;no -> jump move #255,d4 ;limit to highest point bra.b .novariation .water1 add d6,d4 ;add variation to height ble.b .novariation ;still under water? -> jump moveq #0,d4 ;least deep water .novariation tst d5 ;polygon in water? ble.b .water ;yes -> jump sub #255,d4 neg d4 move.b d5,(a0) ;store height in first byte asr #2,d4 ;calc color value bne.b .cont2 ;not zero? moveq #1,d4 ;if zero than one (no water) .cont2 move.b d4,1(a0) ;store color into second byte bra.b .end .water neg d4 asr #2,d4 add #64,d4 ;calc color value clr.b (a0) ;height = 0 cmp #127,d4 ;if water too deep ble.b .cont3 moveq #127,d4 ;limit to darkest blue .cont3 move.b d4,1(a0) ;store color .end movem.l (sp)+,d1-d7/a1 rts ;;/ ;// CreateShadow (calculates the shadow) ****************************************************************************** * * CreateShadow (a0,a1,d0,d1,d2) * * divides the landscape in smaller parts * * In: a0 -> map memory * a1 -> tangens table for tangens calculation * d0 = map border size * d1 = light direction (0-3) * d2 = light angle (0-89) * ****************************************************************************** CreateShadow movem.l d2-d7,-(sp) moveq #8,d3 ;calc tan (lightangle) lsl d3,d2 ext.l d2 divu #90,d2 add d2,d2 move 0(a1,d2.w),d4 ;d4 = tan (angle) << 7 move.l d0,d3 mulu.l d0,d0 add.l d0,d0 ;d0 = map size in bytes tst d1 ;case direction beq.b .left cmp #1,d1 beq.b .top cmp #2,d1 beq.b .right .bottom add.l d0,a0 ;rays from bottom lea -2(a0),a0 ;a0 -> last element in map move.l d3,d6 add.l d6,d6 neg.l d6 ;vertical step value moveq #-2,d5 ;horizontal line step value bra.b .cont .right add.l d0,a0 ;rays from right lea -2(a0),a0 ;a0 -> last element in map move.l d3,d5 add.l d5,d5 neg.l d5 ;horizontal step value moveq #-2,d6 ;vertical line step value bra.b .cont .top move.l d3,d6 add.l d6,d6 moveq #2,d5 bra.b .cont .left moveq #2,d6 move.l d3,d5 add.l d5,d5 .cont move.l d3,d7 subq #1,d7 move.l d3,d0 move.l d4,d1 ext.l d1 move.l d6,d2 .loop bsr ShadowLine ;shadow one line add d5,a0 ;go to next line dbra d7,.loop movem.l (sp)+,d2-d7 rts ;;/ ;// ShadowLine (shadows one map line) ****************************************************************************** * * ShadowLine (a0,d0,d1,d2) * * shadows one map line * * In: a0 -> map memory (or last element) * d0 = map border size * d1 = vertical difference * d2 = map step value * ****************************************************************************** ShadowLine movem.l d0-a2,-(sp) move.l a0,a1 move.l d0,d7 move.l d1,d4 move.l d2,d6 moveq #0,d2 ;init point counter .loop moveq #0,d0 move.b (a0),d0 ;read height lsl #7,d0 ;shift left sub d4,d0 ;subtract tangens .entry add d6,a0 ;goto next point addq #1,d2 cmp d7,d2 ;wrap around? bne.b .cont ;no -> jump move.l a1,a0 ;begin again .cont moveq #0,d1 move.b (a0),d1 ;read height of next pixel lsl #7,d1 cmp d0,d1 ;below shadow line? blt.b .shade ;yes -> shade point cmp d7,d2 ;if no shadow and line done bgt.w .end ;-> exit bra.w .loop ;try next point .shade moveq #0,d3 move.b 1(a0),d3 ;read color value cmp #127,d3 ;already shaded? bgt.b .next ;yes -> jump add #128,d3 ;shade point move.b d3,1(a0) ;store new color value .next sub d4,d0 ;subtract tangens bra.w .entry ;shade next point .end movem.l (sp)+,d0-a2 rts ;;/ ;// SetRNDModeRZ (set rounding mode for the FPU to 'round to zero') ****************************************************************************** * * d0 = SetRNDModeRZ * * set rounding mode for the FPU to 'round to zero' * * Out: d0 = old FPCR value * ****************************************************************************** SetRNDModeRZ fmove.l fpcr,d0 move.l d0,d1 or.l #$00000010,d1 fmove.l d1,fpcr rts ;;/ ;// RestoreRNDMode (restores rounding mode for the FPU) ****************************************************************************** * * RestoreRNDMode (d0) * * restores rounding mode for the FPU * * In: d0 = FPCR value to be restored * ****************************************************************************** RestoreRNDMode fmove.l d0,fpcr rts ;;/ ;// URN30 (calculates one uniform random number) ****************************************************************************** * * d0 = URN30 * * calculates one uniform random number (rounding mode for the FPU * MUST be set to 'round to zero') * 'Code' must hold a start random value if it's first used * URN30 algorithm is taken: Xn+1 = 630360016 * Xn mod $7fffffff * d1-d3,fp0-fp2 are trashed * * Out: d0 = new random number (0-$7ffffffe) * ****************************************************************************** URN30 move.l Code,d0 ;get previous result/start res. move.l #630360016,d1 move.l #$7fffffff,d2 fmove.l d1,fp0 fmove.l d2,fp1 fmove.l d0,fp2 fmul fp0,fp2 mulu.l d1,d0 fdiv fp1,fp2 fmove.l fp2,d3 mulu.l d2,d3 sub.l d3,d0 ;d0 = new random number move.l d0,Code ;store actual result rts ;;/