Texture test

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Texture_test is a basic example plugin. This wiki page is intended as a walkthrough of the code in order to help you better understand the SDK.

_TOC_

Functionality

This plugin is a test of plugin value textures. Basically a type of procedural.

Code Walkthrough

Class declaration

class CTestTexture :
               public CLxImpl_ValueTexture,
               public CLxImpl_ChannelUI
{
   public:
       static LXtTagInfoDesc		 descInfo[];
 
       CTestTexture ();
 
       LxResult		vtx_SetupChannels (ILxUnknownID addChan);
       LxResult		vtx_LinkChannels  (ILxUnknownID eval, ILxUnknownID item);
       LxResult		vtx_ReadChannels  (ILxUnknownID attr, void **ppvData);
       void			vtx_Evaluate      (ILxUnknownID vector, LXpTextureOutput *tOut, void *data);
       void			vtx_Cleanup       (void *data);
 
       LxResult		cui_Enabled           (const char *channelName, ILxUnknownID msg, ILxUnknownID item, ILxUnknownID read);
       LxResult		cui_DependencyCount   (const char *channelName, unsigned *count);
       LxResult		cui_DependencyByIndex (const char *channelName, unsigned index, LXtItemType *depItemType, const char **depChannelName);
 
       LXtItemType		MyType ();
 
       CLxUser_PacketService	pkt_service;
       unsigned		idx_sat, idx_lo, idx_hi;
       unsigned		tin_offset;
       LXtItemType		my_type;
 
       class RendData {
           public:
               float		f_sat, f_base, f_mult;
       };
};

This has the basic ValueTexture interface to support simple multi-effect evaluations, plus the ChannelUI interface for enable states. The local RendData struct is used for storing values used for a specific texture evaluation.

Server Tags

LXtTagInfoDesc	 CTestTexture::descInfo[] = {
       { LXsSRV_USERNAME,	"Test Value Texture" },
       { LXsSRV_LOGSUBSYSTEM,	"val-texture"	},
       { 0 }
};

The tags here indicate that server has the name Test Value Texture with the internal name of val-texture.

Initialize

void
Initialize()
{
       CLxGenericPolymorph		*srv;
   
       srv = new CLxPolymorph<CTestTexture>;
       srv->AddInterface (new CLxIfc_ValueTexture<CTestTexture>);
       srv->AddInterface (new CLxIfc_ChannelUI   <CTestTexture>);
       srv->AddInterface (new CLxIfc_StaticDesc  <CTestTexture>);
       lx::AddServer (SRVs_TEXTURE, srv);
}

This function exports a server of the TEXTURE type dependent on the CTestTexture class with the ValueTexture, ChannelUI, and StaticDesc interfaces.

Helper Functions

#define MIN(a,b)	((a) < (b) ? (a) : (b))
#define MAX(a,b)	((a) < (b) ? (b) : (a))
#define PI		3.14159265
#define TWOPI		(2 * PI)

#define _R		rgb[0]
#define _G		rgb[1]
#define _B		rgb[2]
#define _H		hsv[0]
#define _S		hsv[1]
#define _V		hsv[2]

       static void
RGB2HSV (
       const LXtFVector	 rgb,
       LXtFVector		 hsv)
{
       double			 min, max, delta;

       min = MIN (MIN (_R, _G), _B);
       max = MAX (MAX (_R, _G), _B);
       delta = max - min;

       _V = max;
       if (max)
               _S = delta / max;
       else {
               _S = 0.0;
               _H = 0.0;			// black: hue undefined
               return;
       }

       if (delta) {
               if (_R == max)
                       _H = (_G - _B) / delta;		// between yellow & magenta
               else if (_G == max)
                       _H = (_B - _R) / delta + 2.0;	// between cyan & yellow
               else
                       _H = (_R - _G) / delta + 4.0;	// between magenta & cyan
       }
       else
               _H = 0;

       _H *= (float) (PI / 3.0);
       if (_H < 0)
               _H += (float) TWOPI;
}

       static void
HSV2RGB (
       const LXtFVector	 hsv,
       LXtFVector		 rgb)
{
       double			 f, p, q, t;
       int			 i;

       if (_S < DBL_EPSILON) {
               _R = _G = _B = _V;	// grey
               return;
       }

       f = _H * 3.0 / PI;
       while (f < 0.0)
               f += 6.0;
       while (f >= 6.0)
               f -= 6.0;

       i = floor (f);			// sector 0 to 5
       f = f - i;			// factorial part of Hue
       p = _V * (1.0 - _S);
       q = _V * (1.0 - _S *        f);
       t = _V * (1.0 - _S * (1.0 - f));

       switch (i) {
           case 0:
               _R = _V;
               _G =  t;
               _B =  p;
               break;

           case 1:
               _R =  q;
               _G = _V;
               _B =  p;
               break;

           case 2:
               _R =  p;
               _G = _V;
               _B =  t;
               break;

           case 3:
               _R =  p;
               _G =  q;
               _B = _V;
               break;

           case 4:
               _R =  t;
               _G =  p;
               _B = _V;
               break;

           default:
               _R = _V;
               _G =  p;
               _B =  q;
               break;
       }
}

Utilities for RGB/HSV conversion.

Implementations

LxResult
CTestTexture::vtx_SetupChannels (
       ILxUnknownID		 addChan)
{
       CLxUser_AddChannel	 ac (addChan);
 
       ac.NewChannel (CHANs_SATURATION, "percent");
       ac.SetDefault (1.0, 1);

       ac.NewChannel (CHANs_LOW,	 "percent");
       ac.SetDefault (0.0, 0);

       ac.NewChannel (CHANs_HIGH,	 "percent");
       ac.SetDefault (1.0, 1);

       return LXe_OK;
}

This function creates the channels for the item type using the methods of an AddChannel object.

LxResult
CTestTexture::vtx_LinkChannels (
       ILxUnknownID		 eval,
       ILxUnknownID		 item)
{
       CLxUser_Evaluation	 ev (eval);

       idx_sat = ev.AddChan (item, CHANs_SATURATION);
       idx_lo  = ev.AddChan (item, CHANs_LOW);
       idx_hi  = ev.AddChan (item, CHANs_HIGH);

       tin_offset = pkt_service.GetOffset (LXsCATEGORY_SAMPLE, LXsP_TEXTURE_INPUT);
 
       return LXe_OK;
}

This function attaches the channels to channel evaluation. This gets indices for the channels in attributes through the AddChan method of a User Evaluation object.

       LxResult
CTestTexture::vtx_ReadChannels (
       ILxUnknownID		 attr,
       void		       **ppvData)
{
       CLxUser_Attributes	 at (attr);
       RendData		*rd = new RendData;

       rd->f_sat  = at.Float (idx_sat);
       rd->f_base = at.Float (idx_lo);
       rd->f_mult = at.Float (idx_hi) - rd->f_base;

       ppvData[0] = rd;
       return LXe_OK;
}

This function reads channel values which may have changed. These are stored in the allocated data for later evaluation.

void
CTestTexture::vtx_Evaluate (
       ILxUnknownID		 vector,
       LXpTextureOutput	*tOut,
       void			*data)
{
       RendData		*rd = (RendData *) data;
       LXpTextureInput		*tInp;
       float			 tPos[2], u, v, iu, iv;
       LXtFVector		 hsv, rgb;

       tInp = (LXpTextureInput *) pkt_service.FastPacket (vector, tin_offset);

       tPos[0] = (tInp->axis == 0) ? -tInp->tPos[2] : tInp->tPos[0] + 0.5;
       tPos[1] = (tInp->axis == 1) ? -tInp->tPos[2] : tInp->tPos[1] + 0.5;
       iu = floor (tPos[0]);
       iv = floor (tPos[1]);
       u = tPos[0] - iu - 0.5;
       v = tPos[1] - iv - 0.5;

       hsv[0] = iu / 7.7 + iv * 776.315;
       hsv[1] = 1.0 - u * rd->f_sat;
       hsv[2] = v * rd->f_mult + rd->f_base;
       HSV2RGB (hsv, rgb);

       tOut->direct   = 1;
       tOut->alpha[0] = 1.0;
       tOut->value[0] = LXx_VLEN (rgb);

       if (tInp->context == LXi_TFX_COLOR)
               LXx_VCPY (tOut->color[0], rgb);
}

Evaluate the color at a spot using cached values.

void
CTestTexture::vtx_Cleanup (
        void			*data)
{
       RendData		*rd = (RendData *) data;

       delete rd;
}

Release the cached state after rendering is complete using the RendData class defined in our CTestTexture class.

       LXtItemType
CTestTexture::MyType ()
{
       if (my_type != LXiTYPE_NONE)
               return my_type;

       CLxUser_SceneService	 svc;

       my_type = svc.ItemType (SRVs_ITEMTYPE);
       return my_type;
}

Release the cached state after rendering is complete using the SceneService object.

LXtItemType
CTestTexture::MyType ()
{
       if (my_type != LXiTYPE_NONE)
               return my_type;

       CLxUser_SceneService	 svc;

       my_type = svc.ItemType (SRVs_ITEMTYPE);
       return my_type;
}

Utility to get the type code for this item type, as needed.

LxResult
CTestTexture::cui_Enabled (
       const char		*channelName,
       ILxUnknownID		 msg,
       ILxUnknownID		 item,
       ILxUnknownID		 read)
{
       if (strcmp (channelName, CHANs_SATURATION))
               return LXe_OK;

       CLxUser_Item		 src (item);
       CLxUser_ChannelRead	 chan (read);

       if (chan.FValue (src, CHANs_LOW) != 0.0)
               return LXe_OK;

       if (chan.FValue (src, CHANs_HIGH) != 0.0)
               return LXe_OK;

       CLxUser_Message		 res (msg);

       res.SetCode (LXe_CMD_DISABLED);
       res.SetMsg  ("common", 99);
       res.SetArg  (1, "This only applies when High and Low are non-zero.");
       return LXe_CMD_DISABLED;
}

Test if a given channel is enabled. We're going to disable the saturation channel if both the high and low are set to zero. I'm using common message 99, which just repeats its string argument, but normally this would be defined in a dedicated message table.

LxResult
CTestTexture::cui_DependencyCount (
       const char		*channelName,
       unsigned		*count)
{
       if (strcmp (channelName, CHANs_SATURATION) == 0)
               count[0] = 2;
       else
               count[0] = 0;

       return LXe_OK;
}

       LxResult
CTestTexture::cui_DependencyByIndex (
       const char		*channelName,
       unsigned		 index,
       LXtItemType		*depItemType,
       const char	       **depChannelName)
{
       if (strcmp (channelName, CHANs_SATURATION))
               return LXe_OUTOFBOUNDS;

       depItemType[0] = MyType ();
       switch (index) {
           case 0:
               depChannelName[0] = CHANs_LOW;
               return LXe_OK;

           case 1:
               depChannelName[0] = CHANs_HIGH;
               return LXe_OK;

           default:
               return LXe_OUTOFBOUNDS;
       }
}

Dependency count/byIndex list the channels that affect a given target channel. In our case the saturation channel is affected by changes to the low and high channels of this same item type.