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First ray successfully cast on Apple II.
This commit is contained in:
Martin Haye
parent
906018b6cc
commit
cfe7edcf47
@ -520,7 +520,7 @@ function pow2_w_w(n)
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return result;
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}
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function wallCalc(dist, bDir1, bDir2, bStep2)
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function wallCalc(x, dist, bDir1, bDir2, bStep2)
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{
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// Calculate perpendicular distance. Use logarithms for super-speed.
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dist = abs_w_w(dist);
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@ -533,8 +533,13 @@ function wallCalc(dist, bDir1, bDir2, bStep2)
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bWallX ^= 0xFF;
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// Calculate line height
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sum = log2_w_w(64) - diff;
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lineHeight = uword(pow2_w_w(sum));
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lineHeight = uword(pow2_w_w(log2_w_w(64) - diff));
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if (x == debugRay) {
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console.log(" absDist=$" + wordToHex(dist) +
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", diff=$" + wordToHex(diff) +
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", sum=$" + wordToHex(sum));
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}
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return [lineHeight, bWallX]
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/* No-log algorithm
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@ -635,7 +640,7 @@ function intCast(x)
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var wPerpWallDist = (bMapX<<8) - wRayPosX;
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if (bStepX < 0)
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wPerpWallDist += 256;
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nums = wallCalc(wPerpWallDist, bRayDirX, bRayDirY, bStepY);
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nums = wallCalc(x, wPerpWallDist, bRayDirX, bRayDirY, bStepY);
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lineHeight = nums[0]
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bWallX = nums[1]
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bWallX = uadd_bb_b(bWallX, wRayPosY & 0xFF);
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@ -659,7 +664,7 @@ function intCast(x)
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var wPerpWallDist = (bMapY<<8) - wRayPosY;
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if (bStepY < 0)
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wPerpWallDist += 256;
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nums = wallCalc(wPerpWallDist, bRayDirY, bRayDirX, bStepX);
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nums = wallCalc(x, wPerpWallDist, bRayDirY, bRayDirX, bStepX);
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lineHeight = nums[0];
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bWallX = nums[1];
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bWallX = uadd_bb_b(bWallX, wRayPosX & 0xFF);
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@ -671,10 +676,9 @@ function intCast(x)
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}
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if (x == debugRay) {
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console.log(" abs(wPerpWallDist)=$" + wordToHex(Math.abs(wPerpWallDist)) +
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", lineHeight=$" + wordToHex(lineHeight) +
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", wallType=" + map[bMapY][bMapX] +
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", wallX=$" + byteToHex(bWallX));
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console.log("lineHeight=$" + wordToHex(lineHeight) +
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", wallType=" + map[bMapY][bMapX] +
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", wallX=$" + byteToHex(bWallX));
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}
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// Wrap it all in a nice package.
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@ -319,10 +319,6 @@ pow2_w_w:
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sec ; so we shift a 1 into the high bit of the low byte
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@loLup:
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ror ; shift down
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pha
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jsr prbyte
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jsr crout
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pla
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inx ; count up exponent...
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cpx #8 ; ...until we hit 8
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bcc @loLup ; handy because we need carry to be clear the next go-round
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@ -445,14 +441,13 @@ castRay:
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; We hit something!
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@hitX:
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DEBUG_STR " Hit."
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brk
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sta txNum ; store the texture number we hit
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lda #0
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sec
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sbc playerX ; inverse of low byte of player coord
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sta dist ; is fractional byte of dist.
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lda mapX ; map X is the integer byte
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sbc #0
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sbc playerX+1
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bit stepX
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bmi :+
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ina ; if stepping forward, add one to dist
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@ -469,7 +464,11 @@ castRay:
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bmi :+
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eor #$FF ; ...invert the texture coord
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: sta txColNum
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.if DEBUG
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jmp @debugFinal
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.else
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rts
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.endif
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; taking a step in the Y direction
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@takeStepY:
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tya ; get ready to adjust Y by a whole line
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@ -501,14 +500,13 @@ castRay:
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@hitY:
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; We hit something!
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DEBUG_STR " Hit."
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brk
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sta txNum ; store the texture number we hit
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lda #0
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sec
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sbc playerY ; inverse of low byte of player coord
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sta dist ; is fractional byte of dist.
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lda mapY ; map X is the integer byte
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sbc #0
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sbc playerY+1
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bit stepY
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bpl :+
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ina ; if stepping backward, add one to dist
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@ -525,7 +523,11 @@ castRay:
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bpl :+
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eor #$FF ; ...invert the texture coord
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: sta txColNum
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.if DEBUG
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jmp @debugFinal
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.else
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rts
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.endif
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; wall calculation: X=dir1, Y=dir2, A=dir2step
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@wallCalc:
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@ -537,15 +539,23 @@ castRay:
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stx @sub2+1
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lda dist ; calc abs(dist)
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ldx dist+1 ; dist currently in A(lo)/X(hi)
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bpl :+
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lda #0
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bpl @notNeg
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lda #0 ; invert distance if negative to get absolute value
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sec
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sbc dist
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tay
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lda #0
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sbc dist+1
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tax ; get inverted dist into A(lo)/X(hi)
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tya
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: jsr log2_w_w ; calculate log2(abs(dist))
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@notNeg:
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.if DEBUG
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sta a2l
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stx a2h
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DEBUG_STR " dist="
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DEBUG_WORD a2l
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.endif
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jsr log2_w_w ; calculate log2(abs(dist))
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sec
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@sub1:
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sbc #0 ; subtract log2(dir1)
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@ -554,6 +564,8 @@ castRay:
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@sub2:
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sbc #0
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sta diff+1
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DEBUG_STR "diff="
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DEBUG_WORD diff
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; Calculate texture coordinate
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pla ; get dir2 back
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jsr log2_b_w ; calculate log2(dir2)
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@ -563,6 +575,13 @@ castRay:
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txa
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adc diff+1
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tax
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.if DEBUG
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sty a2l
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stx a2h
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DEBUG_STR "sum="
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DEBUG_WORD a2l
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DEBUG_LN
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.endif
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jsr pow2_w_w ; calculate 2 ^ sum
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; fractional part (A-reg) of result is texture coord
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ply ; retrieve the step direction
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@ -596,6 +615,14 @@ castRay:
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DEBUG_BYTE sideDistY
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DEBUG_LN
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rts
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@debugFinal:
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DEBUG_STR " lineCt="
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DEBUG_BYTE lineCt
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DEBUG_STR "txNum="
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DEBUG_BYTE txNum
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DEBUG_STR "txCol="
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DEBUG_BYTE txColNum
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brk
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.endif
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; Advance pLine to the next line on the hi-res screen
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