Prizm Useful Routines -- post here!

[Ashbad]

This routine will print masked Glyph numbers for you kinda application specific, but others could find use of it.

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void drawprintnum(int x, int y, int num, int width, int height, void*glyph_nums) { int digits[10] = {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1}; int pos_num = (num<0)?(-num):(num); int num_digits = 0; for(int i = 0; i < 10; i++) { if(!pos_num) { break; } digits[i] = pos_num%10; pos_num = (pos_num - (pos_num%10)) / 10; num_digits++; } if(num<0) { CopySpriteMasked(glyph_nums + (width*height*2*10), x, y, width, height, 0xFFFF); x += width+2; } else if (num == 0) { CopySpriteMasked(glyph_nums, x, y, width, height, 0xFFFF); return; } for(int i = 0; i < num_digits; i++) { CopySpriteMasked((digits[i]*(width*height*2))+glyph_nums, x, y, width, height, 0xFFFF); x += width+2; } }

[Eiyeron]

Is any routine to draw some sprites with alpha based on a colour?

[z80man]

I assume you mean that the alpha color is supplied at runtime and is only a single bit of alpha meaning that every pixel is either opaque or fully transparent. Here's what I got, it should do the trick. It's pretty simple and do note that it doesn't support clipping so if you need that ask and I'll write another routine.

Edit: fixed bug
Edit2: fixed another bug

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#define WIDTH 384 #define HEIGHT 216 short * VRAM = (short*) GetVRAMAddress(); void alphaSprite(int x, int y, int width, int height, short * bitmap, short alpha) {      int y_index;      int x_index;      short * base = y * WIDTH + x + VRAM;      for (y_index = height; y_index > 0; --y_index, base += WIDTH - width)      {           for (x_index = width; x_index > 0; --x_index, ++base, ++bitmap)           {                if (*bitmap != alpha) *base = *bitmap;           }      } }

[calc84maniac]

I think if (*base != alpha) should be if (*bitmap != alpha) because you want that color in the bitmap to cause transparency, not that color in VRAM.

Edit: Also, base += WIDTH should be base += WIDTH - width because base was increased by the inner loop.

[z80man]

I think if (*base != alpha) should be if (*bitmap != alpha) because you want that color in the bitmap to cause transparency, not that color in VRAM.

Edit: Also, base += WIDTH should be base += WIDTH - width because base was increased by the inner loop.

Good eye there. I was umm testing you for your ability to catch my on purpose mistakes 

The error has been fixed in my above post

[Eiyeron]

I should have clip' too, may you do it, please?

[z80man]

I should have clip' too, may you do it, please?

Sure, I based this example off my previous routine but with some more work I can get a more optimized version out.

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#define WIDTH 384 #define HEIGHT 216 short * VRAM = (short*) GetVRAMAddress(); void alphaSprite(int x, int y, int width, int height, short * bitmap, short alpha) {      int y_index;      int x_index;      short * base = y * WIDTH + x + VRAM;      if (y < 0)      {           base += (y & 0x8fffffff) * WIDTH;           bitmap += (y & 0x8fffffff) * WIDTH;           height += y;           y = 0;      }      if (height > HEIGHT) height = HEIGHT + y;      for (y_index = height; y_index > 0; --y_index, base += WIDTH - width, bitmap += x_inc)      {                      for (x_index = width; x_index > 0; --x_index, ++base, ++bitmap)           {                if (*bitmap != alpha) *base = *bitmap;           }      } }

[calc84maniac]

Okay, that routine is kind of messed up, so here is what I believe to be a fixed version (by the way, y & 0x8FFFFFFF is not even CLOSE to -y)

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#define WIDTH 384 #define HEIGHT 216 short * VRAM = (short*) GetVRAMAddress(); void alphaSprite(int x, int y, int width, int height, short * bitmap, short alpha) { int x_inc = width; if (y < 0) { bitmap -= y * x_inc; height += y; y = 0; } if (height > HEIGHT - y) height = HEIGHT - y; if (x < 0) { bitmap -= x; width += x; x = 0; } if (width > WIDTH - x) width = WIDTH - x; int y_index; int x_index; short * base = y * WIDTH + x + VRAM; for (y_index = height; y_index > 0; --y_index, base += WIDTH - width, bitmap += x_inc) { for (x_index = width; x_index > 0; --x_index, ++base, ++bitmap) { if (*bitmap != alpha) *base = *bitmap; } } }

Edit: I just noticed the x_inc in your code that you never initialized, edited my code to include that.

[z80man]

I guess that what happens when you code with little sleep and don't have access to a test platform
The x_inc I used (and must of accidentally deleted) is for how much the bitmap pointer needs to be incremented every time a new row is drawn. It is left at zero unless the bitmap overlaps either or both the left and right edges, Here is what I modified to hopefully work. Also one thing that I forgot to do is add some pointer type casts as even though I'm pretty sure  gcc will compile this, g++ could have some issues de to the stronger C++ rules about type casts.

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#define WIDTH 384 #define HEIGHT 216 short * VRAM = (short*) GetVRAMAddress(); void alphaSprite(int x, int y, int width, int height, short * bitmap, short alpha) { int x_inc = 0; if (y < 0) { bitmap -= (short*)(y * width); height += y; y = 0; } if (height > HEIGHT - y) height = HEIGHT - y; if (x < 0) {                 bitmap -= (short*)x; width += x; x = 0;                 x_inc += -x; } if (width > WIDTH - x)         {              width = WIDTH - x;      x_inc += WIDTH - (width + x);         } int y_index; int x_index; short * base = (short*)(y * WIDTH) + x + VRAM; for (y_index = height; y_index > 0; --y_index, base += (short*)WIDTH - width, bitmap += (short*)x_inc) { for (x_index = width; x_index > 0; --x_index, ++base, ++bitmap) { if (*bitmap != alpha) *base = *bitmap; } } }

[calc84maniac]

Eww bad bad typecasts. They won't work (ever try adding a short* to a short*?) and they're just not needed. Adding an int to a pointer is the preferred method for offsetting anyway.

[z80man]

Eww bad bad typecasts. They won't work (ever try adding a short* to a short*?) and they're just not needed. Adding an int to a pointer is the preferred method for offsetting anyway.

It's been awhile since I did some heavy messing around with type casts. Looks like I forgot that adding an int to a pointer results in an implicit type cast. All of my programming class stuff (which is in java) makes pointers a lot harder when I come back to C especially because java is very strongly typed.

[calc84maniac]

Eww bad bad typecasts. They won't work (ever try adding a short* to a short*?) and they're just not needed. Adding an int to a pointer is the preferred method for offsetting anyway.

It's been awhile since I did some heavy messing around with type casts. Looks like I forgot that adding an int to a pointer results in an implicit type cast. All of my programming class stuff (which is in java) makes pointers a lot harder when I come back to C especially because java is very strongly typed.

Adding an int to a pointer results in a pointer. There's no implicit typecast at all, that's just how it's defined.

[z80man]

Perhaps this should be tested but atm I don't have a program set up nor the time because I have plenty of homework to do
Maybe if I have some time later I'll have some alpha based sprite run around the screen and go through the edges.

[Eiyeron]

Thanks, what version should I use? (any name given in the credits, too?)

[calc84maniac]

Here's a version of my code with fixed x_inc handling (his latest code doesn't work due to the typecasting)

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#define WIDTH 384 #define HEIGHT 216 short * VRAM = (short*) GetVRAMAddress(); void alphaSprite(int x, int y, int width, int height, short * bitmap, short alpha) { int x_inc = width; if (y < 0) { bitmap -= y * width; height += y; y = 0; } if (height > HEIGHT - y) height = HEIGHT - y; if (x < 0) { bitmap -= x; width += x; x = 0; } if (width > WIDTH - x) width = WIDTH - x; x_inc -= width; int y_index; int x_index; short * base = y * WIDTH + x + VRAM; for (y_index = height; y_index > 0; --y_index, base += WIDTH - width, bitmap += x_inc) { for (x_index = width; x_index > 0; --x_index, ++base, ++bitmap) { if (*bitmap != alpha) *base = *bitmap; } } }