[cpctelera] cpct_drawSpriteBlended problem

[EgoTrip]

I can't get  cpct_drawSpriteBlended to work. All I get is a garbled mess as in the image.

Also, having the parameters in a different order to the rest of the sprite commands is confusing. Can I suggest having them all in the same order?

[SRS]

To change the parameter order to "norm" (void* *sprite*, void* *memory*, <u8> *width*, <u8> *height*) this could help:

change part of "cpct_drawSpriteBlended_cbindings.s"

to

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_cpct_drawSpriteBlended::
   ;; GET Parameters from the stack
   pop  hl     ;; [3] HL = Return Address
   pop  bc     ;; [3] BC = Height/Width (C = Width, B = Height)
   ld a,c      ;; change b/c
   ld c,b
   ld b,a
   pop  de     ;; [3] DE = Destination address (Video memory location)
   ex (sp), hl ;; [6] HL = Source Address (Sprite data array)
               ;; ... And put returning address in the stack again
               ;;      as this function uses __z88dk_callee convention

.include /cpct_drawSpriteBlended.asm/

[ronaldo]

@EgoTrip : Can you show me the code you are using? I cannot imagine what's happenning to you without having a deeper look at it .

Order of parameters is always selected to improve performance of the function. That's the reason why some of them are in different orders: it depends on implementation.

However, there is an easy way to change parameter order of any function: you may define a custom macro. For instance, to change parameter order of cpct_drawSpriteBlended you may do this:

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  // Change parameter order of cpct_drawSpriteBlended(memory, height, width, sprite)
  #define drawSpBlended(S,M,H,W) cpct_drawSpriteBlended( (M), (H), (W), (S) )

  //.... After some code, we use our macro ...
  drawSpBlended(mySprite, CPCT_VMEM_START, SP_WIDTH, SP_HEIGHT);


That should do the trick for you, without losing bytes/time and without having to compile CPCtelera again.

[SRS]

Makros - never think of them if I can recode something

[EgoTrip]

the code is literally this:

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pvideomem = cpct_getScreenPtr((u8*)0xC000, 48, 128);
cpct_drawSpriteBlended(pvideomem,4,16,frame);

where frame is the sprite pointer.

I gave up on it and used masked sprites in the end. I am sticking with masked sprites for this game now anyway as I have put in backgrounds and its easier to just redraw them than XOR and have messed up colours.

[ronaldo]

Is your sprite 8-mode-0-pixels or 16-mode-1-pixels wide?

SideNote: In the present version of CPCtelera, there is a macro called cpctm_screenPtr that works similar to cpct_getScreenPtr but is advisable for constant values. Constant values yield always same result, so calling cpct_getScreenPtr for them wastes time on calculating the resulting value. cpctm_screenPtr does this calculation during compile time, and your final binary only gets the final constant value, saving you CPU time.

[EgoTrip]

16 mode 1

[ronaldo]

Does your sprite have interlaced mask or not?

[EgoTrip]

Does your sprite have interlaced mask or not?

No not that one, its just a standard sprite.

[ronaldo]

Ok then. Can you attach me your project including the sprite to check what happens?

[EgoTrip]

I just do it in a new project. Just that code, and this sprite:

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const u8 G_S07_Jewel[64] = {
    0xF0, 0xF0, 0xF0, 0xF0,
    0xE0, 0xA0, 0xA0, 0xB0,
    0xC0, 0x00, 0x00, 0x10,
    0x91, 0xFF, 0xFF, 0x10,
    0xB2, 0xF0, 0xF0, 0x98,
    0xE4, 0x77, 0xDE, 0xD4,
    0xC8, 0x77, 0xCF, 0xF2,
    0xC8, 0x77, 0xCF, 0x7A,
    0xFB, 0x8F, 0x0C, 0x72,
    0xF5, 0x8F, 0x0C, 0xE4,
    0x32, 0xCF, 0x18, 0x88,
    0x11, 0xC7, 0x39, 0x80,
    0x30, 0xEB, 0x62, 0x00,
    0x40, 0x65, 0xC4, 0x20,
    0x00, 0x32, 0xC8, 0x00,
    0xA0, 0xF1, 0xE0, 0xA0};

[ronaldo]

Oh, man, blimey! Height and width were inverted and none of use did notice 

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   // Draw the sprite to screen with blending
   cpct_drawSpriteBlended(p, height, width, sprite);


So, your code should be,

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   cpct_drawSpriteBlended(pvideomem, 16, 4, frame);


I clearly agree with you, parameters are confusing. For next version I'll think about including macros with a standard order by default.


I recommend you to include and use this macro in your code

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  // Change parameter order of cpct_drawSpriteBlended(memory, height, width, sprite)
  #define drawSpBlended(S,M,H,W) cpct_drawSpriteBlended( (M), (H), (W), (S) )


[EgoTrip]

Thanks