Twister problem

[Positron]

I'm trying to code a twister, but it's looking wrong.
I can't find the problem. It would be fine, if someone has an idea.

Code Select Expand


m_hr = mpBack->LockRect(&Rect,NULL,0);
if (m_hr == D3D_OK)
{
DWORD *pMem = (DWORD*) Rect.pBits;
int corPitch = Rect.Pitch /4;
for(int x=x_max-1;x>0;x--)
{

lstRubber[x].py[0] = (float)lstRubber[x-1].py[0];
lstRubber[x].py[1] = (float)lstRubber[x-1].py[1];
lstRubber[x].py[2] = (float)lstRubber[x-1].py[2];
lstRubber[x].py[3] = (float)lstRubber[x-1].py[3];
}

lstRubber[0].py[0] = (y_mul * sinf((mPos*oneD)))+y_ofs;
lstRubber[0].py[1] = (y_mul * sinf((mPos+90.0f)*oneD))+y_ofs;
lstRubber[0].py[2] = (y_mul * sinf((mPos+180.0f)*oneD))+y_ofs;
lstRubber[0].py[3] = (y_mul * sinf((mPos+270.0f)*oneD))+y_ofs;
DWORD* pTex = (DWORD*) Textures[0];
float xTexStep = x_max/256.0f;
float xTexPos  = 0.0f;
float yTexStep = 0.0f;

for(int x=0;x<x_max;x++)
{
int y2;
for (int i = 0; i<4;i++)
{
if (i==3)
y2 = 0;
else
y2 = i+1;

if (lstRubber[x].py[y2]>lstRubber[x].py[i])
{
float linLength = lstRubber[x].py[y2]-lstRubber[x].py[i];

float colorMul =linLength/y_mul;
//float colorMul = 1.0f;
yTexStep = linLength/256.0f;
float yTexPos = 0.0f;
int tmpX = xTexPos;
for (int y = lstRubber[x].py[i]; y <= lstRubber[x].py[y2]; y++)
{
int tmpY = yTexPos;

DWORD thisColor = pTex[tmpY*256+tmpX];
DWORD red = (UINT)(((thisColor & 0x00ff0000) >> 16) * colorMul);
DWORD green = (UINT)(((thisColor & 0x0000ff00) >> 8) * colorMul);
DWORD blue = (UINT)((thisColor & 0x000000ff) * colorMul);
thisColor = 0xff000000 | (red <<16) | (green<<8) | blue;
pMem[(y* corPitch)+x] = thisColor;
yTexPos += yTexStep;
}
}
}
xTexPos += xTexStep;

}


[Shockwave]

I can't start your application here for some reason, looking through your code though I think you are over complicating it.

You should be able to draw the whole twister in one loop.

I will explain the technique which is very simple. I should know, I've made loads of them
Let's suppose that you have 4 sides on your twister and that your screen is 480 pixels tall, you could use any resolution you want.

This will be done in pseudo code as C++ is not my own language of choice.


FOR Y = 0 TO 479

First calculate 4 points;

X1 = 100 + 50 * SIN ( ANGLE + Y )
X2 = 100 + 50 * SIN ( (ANGLE+90) + Y )
X3 = 100 + 50 * SIN ( (ANGLE+180) + Y )
X4 = 100 + 50 * SIN ( (ANGLE+270) + Y )

Then we do a simple test to see if the line is visible and then draw it if it is;

IS X2>X1? IF YEST DRAW LINE FROM X1 TO X2
IS X3>X2? IF YEST DRAW LINE FROM X2 TO X3
IS X4>X3? IF YEST DRAW LINE FROM X3 TO X4
IS X1>X4? IF YEST DRAW LINE FROM X4 TO X1

NEXT Y

A few points of interest, you should add something to the variable ANGLE each frame so that the twister rotates.

You'll notice also that ANGLE+90 etc, as the points of a square are at 90 degree intervals, that's why we do this.


You can make the calculation to generate the points a little bit more interesting if you want to make a more pleasing twister.

I am working on one at the moment, the source is in Freebasic though if you'd like to look at it it is not a problem.

[Paul]

I don't know about your twister but the rest is looking good except for one thing, the round vista loading pointer is showing in the middle of everything.

[Positron]

I think you are over complicating it.

This is the result of two days error seeking. 

You can make the calculation to generate the points a little bit more interesting if you want to make a more pleasing twister.
I am working on one at the moment, the source is in Freebasic though if you'd like to look at it it is not a problem.

Sure I'm interested in. It's allway nice to have the chance to learn.

I will throw away the source and start coding again. I think tomorrow I can tell more.

Btw. how that karma thing is working?

And thanks of course!

I don't know about your twister but the rest is looking good except for one thing, the round vista loading pointer is showing in the middle of everything.

Just now I haven't got Vista, but I try to get my hands on soon.

[Positron]

I can't start your application here for some reason,

This exe don't start here neither. The next exe will. 

[Jim]

It starts OK for me
Here's the source for another twisting bar demo
http://dbfinteractive.com/index.php?topic=752.0
I thnk it's a little less complicated than some others, but the maths might not be as obvious!
You can download the yabasic player here http://dbfinteractive.com/index.php?topic=758.0

Jim

[va!n]

@Jim:
Very very nice example! K++

@all:
Here is my first try to code a nice and cool oldskool twister effect... i will release the PB source when i have cleaned it up a bit ^^

[Positron]

@Jim, Va!n
Thanks!

After I have coded the whole thing again everything works fine. I don't know what was wrong by the first attempt.
I will post the twister-source after I have released this intro.

[benny!]

@sw:
Again, awesome kind of little tutorial. Well done!

@va!n:
Nice PB conversion - runs like a charme here !!!

@Positron:
Looking forward to see the intro. When do you think you gonna release it ?

[Positron]

@Positron:
Looking forward to see the intro. When do you think you gonna release it ?

I haven't got a fixed plan for release date. Possibly this weekend.

[Shockwave]

Looking forward to it

Make sure that you adda little test to see how long the line you are drawing is, the longer the line, the lighter the colour and it will have a nice fake light sourcing effect.

And then if you really want to hide the fake light sourcing, you can draw some metaballs over the top to give a specular highlight sort of effect

[Positron]

Make sure that you adda little test to see how long the line you are drawing is, the longer the line, the lighter the colour and it will have a nice fake light sourcing effect.

I have already done the fake light sourcing effect. Looks nice.

Your intro looks very nice. Already planned a release date?

[Shockwave]

Ehm, well I am waiting for a song from Ampli and the scroll texts from some other S!P members before I can release I think yours will be released first, Ampli is quite busy with work at the moment.

[Positron]

Song! 
Dawned I forgot we have no song. I think no release this weekend!

[Positron]

Hey,

I can give karma now.

Shockwave k++ for always being helpful!

[Shockwave]

Thanks

Btw, sorry I should have added a description about Karma somewhere on the forum, people with more than 25 posts can give good or bad karma every 3 hours

[va!n]

Sorry for the big delay due fact of some internet provider problems... here you will find a PB source version...

http://dbfinteractive.com/index.php?topic=2430.0

[Positron]

@Va!n
Thanks.
The twister already works. Now I'm waiting for the gfx and maybe I change the design a little bit.
Than I will release it.