I've got goo news and bad news: the good news: I've got affine texture mapping to work on a computer. The bad news: I can't get it to work on a calc.
what am I doing wrong?

Computer	Calculator
Everything works just the way it's supposed to.	In the first step (TriangleDrawLoop1), it just draws black pixels, and in the secound draw loop, nothing is drawn.
Spoiler For GML source code: dx1 = (x2-x1)/(y2-y1) dx2 = (x3-x2)/(y3-y2) dx3 = (x3-x1)/(y3-y1) du1 = (u2-u1)/(y2-y1) du2 = (u3-u2)/(y3-y2) du3 = (u3-u1)/(y3-y1) dv1 = (v2-v1)/(y2-y1) dv2 = (v3-v2)/(y3-y2) dv3 = (v3-v1)/(y3-y1) tx1 = x1 tx2 = x1 tu1 = u1 tu2 = u1 tv1 = v1 tv2 = v1 surf = surface_create(24,24) surface_set_target(surf) draw_sprite(sprite0,-1,0,0) surface_reset_target(); for(ty = y1; ty < y2; ty += 1){     //draw_line(tx1,ty,tx2,ty)     for(tx = tx2; tx <= tx1; tx += 1){         if(tx1==tx2){             tmp = 0         }else{             tmp = (tx - tx2)/(tx1-tx2)         }         draw_point_color(tx,ty,surface_getpixel(surf,floor((1-tmp)*tu2+tmp*tu1),floor((1-tmp)*tv2+tmp*tv1)))     }     tx1 += dx1     tx2 += dx3     tu1 += du1     tu2 += du3     tv1 += dv1     tv2 += dv3 } for(ty = y2; ty <= y3; ty += 1){     //draw_line(tx1,ty,tx2,ty)     for(tx = tx2; tx <= tx1; tx += 1){         if(tx1==tx2){             tmp = 0         }else{             tmp = (tx - tx2)/(tx1-tx2)         }         draw_point_color(tx,ty,surface_getpixel(surf,floor((1-tmp)*tu2+tmp*tu1),floor((1-tmp)*tv2+tmp*tv1)))     }     tx1 += dx2     tx2 += dx3     tu1 += du2     tu2 += du3     tv1 += dv2     tv2 += dv3 } draw_surface_stretched(surf,300,0,100,100) surface_free(surf) A surface is almost the same as a sprite.	Spoiler For z80 source: DrawTriangle:   ld a, (x1)   ld b, a   ld a, (x2)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y2)   sub b   ld d, a   ld e, 0   call DivFP   ld (dx1), hl   ld a, (x2)   ld b, a   ld a, (x3)   sub b   ld h, a   ld l, 0   ld a, (y2)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (dx2), hl   ld a, (x1)   ld b, a   ld a, (x3)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (dx3), hl   ld a, (u1)   ld b, a   ld a, (u2)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y2)   sub b   ld d, a   ld e, 0   call DivFP   ld (du1), hl   ld a, (u2)   ld b, a   ld a, (u3)   sub b   ld h, a   ld l, 0   ld a, (y2)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (du2), hl   ld a, (u1)   ld b, a   ld a, (u3)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (du3), hl   ld a, (v1)   ld b, a   ld a, (v2)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y2)   sub b   ld d, a   ld e, 0   call DivFP   ld (dv1), hl   ld a, (v2)   ld b, a   ld a, (v3)   sub b   ld h, a   ld l, 0   ld a, (y2)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (dv2), hl   ld a, (v1)   ld b, a   ld a, (v3)   sub b   ld h, a   ld l, 0   ld a, (y1)   ld b, a   ld a, (y3)   sub b   ld d, a   ld e, 0   call DivFP   ld (dv3), hl   ld a, (x1)   ld h, a   ld l, 0   ld (tx1), hl   ld (tx2), hl   ld a, (u1)   ld h, a   ld l, 0   ld (tu1), hl   ld (tu2), hl   ld a, (v1)   ld h, a   ld l, 0   ld (tv1), hl   ld (tv2), hl   ld a, (y1)   ld (_ty), a TriangleDrawLoop1:   ld hl, (tx2)   ld a, h   ld (temp), a TrianglePlotLoop1:   ld hl, (tx1)   ld de, (tx2)   subFP   push hl   ld a, (temp)   ld h, a   ld l, 0   ld de, (tx2)   subFP   pop de   call DivFP   ld (temp2), hl   ;tmp = temp2   ld hl, $0100   ld de, (temp2)   subFP   ld bc, (tu2)   call MulFP   push de   ld hl, (temp2)   ld bc, (tu1)   call MulFP   pop hl   add hl, de   ld a, h   ld (temp3), a      ;u = temp3   ld hl, $0100   ld de, (temp2)   subFP   ld bc, (tv2)   call MulFP   push de   ld hl, (temp2)   ld bc, (tv1)   call MulFP   pop hl   add hl, de   ld a, h   ld (temp3+1), a   ;v = temp3+1   ld a, (temp3+1)   ld l, a   ld h, 0   ld de, texture   add hl, de   ld a, (temp3)   ld b, a   inc b   ld a, (hl)   ld c, a TshiftLoop1:   rl   c   djnz   TshiftLoop1   push af     ld a, (_ty)   ld l, a   ld a, (temp)      ;tx = temp   call GetPixel   ld b, a   pop af   jr c, TSetPixel1 TResPixel1:   ld a, b   cpl   and (hl)   ld (hl), a   jr TEndPlot1 TSetPixel1:   ld a, b   or (hl)   ld (hl), a TEndPlot1:   ld hl, temp   inc (hl)   ld a, (tx1+1)   cp (hl)   jp nc, TrianglePlotLoop1   ld hl, (tx1)   ld de, (dx1)   add hl, de   ld (tx1), hl   ld hl, (tx2)   ld de, (dx3)   add hl, de   ld (tx2), hl   ld hl, _ty   inc (hl)   ld a, (y2)   cp (hl)   jp nc, TriangleDrawLoop1   ld a, (x2)   ld h, a   ld l, 0   ld (tx1), hl TriangleDrawLoop2:   ld hl, (tx2)   ld a, h   ld (temp), a TrianglePlotLoop2:   ld hl, (tx1)   ld de, (tx2)   subFP   push hl   ld a, (temp)   ld h, a   ld l, 0   ld de, (tx2)   subFP   pop de   call DivFP   ld (temp2), hl   ;tmp = temp2   ld hl, $0100   ld de, (temp2)   subFP   ld bc, (tu2)   call MulFP   push de   ld hl, (temp2)   ld bc, (tu1)   call MulFP   pop hl   add hl, de   ld a, h   ld (temp3), a      ;u = temp3   ld hl, $0100   ld de, (temp2)   subFP   ld bc, (tv2)   call MulFP   push de   ld hl, (temp2)   ld bc, (tv1)   call MulFP   pop hl   add hl, de   ld a, h   ld (temp3+1), a   ;v = temp3+1   ld a, (temp3+1)   ld l, a   ld h, 0   ld de, texture   add hl, de   ld a, (temp3)   ld b, a   inc b   ld a, (hl)   ld c, a TshiftLoop2:   rl   c   djnz   TshiftLoop2   push af     ld a, (_ty)   ld l, a   ld a, (temp)      ;tx = temp   call GetPixel   ld b, a   pop af   jr c, TSetPixel2 TResPixel2:   ld a, b   cpl   and (hl)   ld (hl), a   jr TEndPlot2 TSetPixel2:   ld a, b   or (hl)   ld (hl), a TEndPlot2:   ld hl, temp   inc (hl)   ld a, (tx1+1)   cp (hl)   jp nc, TrianglePlotLoop2   ld hl, (tx1)   ld de, (dx2)   add hl, de   ld (tx1), hl   ld hl, (tx2)   ld de, (dx3)   add hl, de   ld (tx2), hl   ld hl, _ty   inc (hl)   ld a, (y2)   cp (hl)   jp nc, TriangleDrawLoop2   ret getPixel:    ld   h, 0    ld   d, h    ld   e, l        add   hl, hl    add   hl, de    add   hl, hl    add   hl, hl        ld   e, a    srl   e    srl   e    srl   e    add   hl, de        ld   de, PlotSScreen    add   hl, de        and   7    ld   b, a    ld   a, $80    ret   z        rrca    djnz   $-1    ret Generated by the BBCode Converter (http://clrhome.tk/resources/bbify/)

What am i doing wrong?

did that basic to assembly source conversion thing work at all?

nope, I haven't found any program that actually converts anything, so I've ported it manually, but i must have made a mistake, ass this is clearly not doing what it should do.

BTW: this routine draws the triangle from top to bottom, which means that the points needs to be in the right order, so does anybody knows a routine to sort the points based on their Y coordinate?

Maybe it does help. If i know how it should be done, then i might be able to rewrite it in asm. And i need a good sorting algorithm for when i'm going to add z-ordering to the engine.

EDIT: I just found a mistake in my code, and now, the triangle is fully drawn, but still just solid black.

EDIT2: I just noticed an other mistake in the source, which made texture mapping impossible. This was not the full cause of the texture not being mapped, however, ass the routine is still drawing a solid black triangle.

EDIT3: Finally!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


the third mistake was caused by a very stupid mistake: I have a text file in the project folder named 'Routines.txt', in which all names of all routines in my app are written, with the arguments and the registers that they destroy. A while ago, i replaced the fixed-point multiplication routine, which had other arguments, so this problem was caused by an outdated routines file

EDIT4: it now draws only 1.29 triangles every second, but I'm optimizing it right now. The first thing I'll do is replace the fixed-point math for every pixel with a much simpler one, which only has to be calculated for each horizontal line. The rest of the line can then be calculated with a simple add command. An other optimization I'll try to add is calling getPixel only once for every scan line, instead of every pixel, then using a right rotation to get the mask.

It seems like if it first draws everything and then deletes the other parts again.

maybe the program draws everything the first tim, but only draws a part of it again, it you toggle the camera!

Although I know it isn't working correctly right now, this is amazing!
I would never have the patience to debug/ create as much as you have.
I hope you find the errors, it seems like you kinda know where the code freaks out.

This is the start and loop code: I don't think anything is set or reset:
the 3D engine is passing the same arguments to it, so i guess the trianlge drawing routine itself couses it, most lickely in the texture handling code 'couse it's the texture that got messed up
Start:
  di
  call ClearGbuf
  call fastCopy
  ld a, 64*3
  ld (direction), a
  in a,($02)
  rla
  sbc a, a
  out ($20), a

  ld hl, 0
  ld (x), hl
  ld hl, $0200
  ld (y), hl

SpelLus:
  call ClearGBuf

  ld a, $FF
  ld (plotsscreen), a
  ld hl, plotsscreen
  ld de, plotsscreen+1
  ld bc, 767
  ldir

  ld hl, (x)
  ld (xfrom), hl
  ld hl, (y)
  ld (yfrom), hl
  ld hl, 0
  ld (zfrom), hl
  ld (zto), hl
  ld a, 64
  ld b, a
  ld a, (direction)
  add a, b
  call SinA
  ld de, (x)
  add hl, de
  ld (xto), hl
  ld a, (direction)
  call SinA
  ld de, (y)
  add hl, de
  ld (yto), hl
  ld hl, $0100
  ld (zup), hl
  ld hl, 0
  ld (xup), hl
  ld (yup), hl
  call InitView

  ld hl, -256
  ld (xpoint), hl
  ld hl, 0
  ld (ypoint), hl
  ld hl, -$0100
  ld (zpoint), hl
  call C3DTo2D
  ld hl, (screenx)
  ld (screenx2), hl
  ld hl, (screeny)
  ld (screeny2), hl
  ld hl, 256
  ld (xpoint), hl
  ld hl, 0
  ld (ypoint), hl
  ld hl, -$0100
  ld (zpoint), hl
  call C3DTo2D
  ld hl, (screenx)
  ld (screenx3), hl
  ld hl, (screeny)
  ld (screeny3), hl
  ld hl, -256
  ld (xpoint), hl
  ld hl, 0
  ld (ypoint), hl
  ld hl, $0100
  ld (zpoint), hl
  call C3DTo2D

  ld a, (screenx)
  ld (x1), a
  ld a, (screeny)
  ld (y1), a
  ld a, 0
  ld (u1), a
  ld (v1), a
  ld a, (screenx2)
  ld (x2), a
  ld a, (screeny2)
  ld (y2), a
  ld a, 0
  ld (u2), a
  ld a, 8
  ld (v2), a
  ld a, (screenx3)
  ld (x3), a
  ld a, (screeny3)
  ld (y3), a
  ld a, 8
  ld (u1), a
  ld (v1), a

  call DrawTriangle

  call FastCopy
 
  ;knoppen
  ld a, $FE
  out (1), a
  in a, (1)
  bit 0, a
  call z, MoveBack
  bit 3, a
  call z, MoveForward
  bit 1, a
  call z, TurnLeft
  bit 2, a
  call z, TurnRight
  ld a, %11111101
  out ($01), a
  in a, ($01)
  bit 6, a
  jp z, Einde
  jp spelLus
 
MoveBack:
  push af
  ld a, (direction)
  ld b, 64
  add a, b
  call SinA
  call NegHL
  ld de, $0A00
  call DivFP
  ld de, (X)
  add hl, de
  ld (X), hl
  ld a, (direction)
  call SinA
  call NegHL
  ld de, $0A00
  call DivFP
  ld de, (Y)
  add hl, de
  ld (Y), hl
  pop af
  ret
MoveForward:
  push af
  ld a, (direction)
  ld b, 64
  add a, b
  call SinA
  ld de, $0A00
  call DivFP
  ld de, (X)
  add hl, de
  ld (X), hl
  ld a, (direction)
  call SinA
  ld de, $0A00
  call DivFP
  ld de, (Y)
  add hl, de
  ld (Y), hl
  pop af
  ret
TurnLeft:
  push af
  ld a, (direction)
  inc a
  ld (direction), a
  pop af
  ret
TurnRight:
  ld a, (direction)
  dec a
  ld (direction), a
  ret
 
Einde:
  ;Key port resetten
  ld a, $FF
  out ($01), a
  call ClearGbuf
  call fastCopy
  ld hl, 0
  ld (CurRow), hl
  EI
  bjump(_JForceCmdNoChar)

That looks very nice, good job. Is this for some other project?