Difference between revisions of "Texture test"

From The Foundry MODO SDK wiki
Jump to: navigation, search
Line 200: Line 200:
 
         ...
 
         ...
 
  }
 
  }
<syntaxhighlight>
+
</syntaxhighlight>
  
 
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.
 
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.

Revision as of 19:16, 16 September 2013

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.

This plugin is a test of plugin value textures, essentially a type of procedural.

Code Walkthrough

Class declaration

We want to create a custom value texture, so we inherit from CLxImpl_ValueTexture, which has all the methods for creating a value texture. We then redeclare most of the methods in the CLxImpl_ValueTexture class(they are the ones with the vtx prefixes) and customize the functions to our specifications. The first three functions set up and access the channels we want to use for our texture. The Evaluate function then evaluates the color of the function using the values of the channels that we have accessed. Finally, the cleanup function releases the cached state after the evaluate function is finished rendering.

We also want to customize and create a ui for our channels, so we inherit from CLxImpl_ChannelUI. We then redeclare three of the functions contained in CLxImpl_ChannelUI. They cui_Enabled function indicates that we turn on the channel ui. The DependencyCount and DependencyByIndex functions list the channels that affect a given target channel.

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.

 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;
        };
 };

Server Tags

Servers tags are examined when the server is initialized, and give information about the server. We set the tags in this case by taking descinfo[] arrays and associating the relevant data with the corresponding flags.

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

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

Initialize

Servers are extensible set of features that we add to modo, usually through plugins. Intialize is called when we add the plugin to modo, and is the utility that exports the server.

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

 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);
 }

Helper Functions

Utilities for RGB/HSV conversion. The second utility is used in the vtx_evaluate function.

 #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)
 {
        ...
 }
 
        static void
 HSV2RGB (
        const LXtFVector	 hsv,
        LXtFVector		 rgb)
 {
    ...
 }

Implementations

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

 LxResult
 CTestTexture::vtx_SetupChannels (
        ILxUnknownID		 addChan)
 {
       ...
 }

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_LinkChannels (
        ILxUnknownID		 eval,
        ILxUnknownID		 item)
 {
        ...
 }

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

        LxResult
 CTestTexture::vtx_ReadChannels (
        ILxUnknownID		 attr,
        void		       **ppvData)
 {
       ...
 }

Evaluate the color at a spot using cached values.

 void
 CTestTexture::vtx_Evaluate (
        ILxUnknownID		 vector,
        LXpTextureOutput	*tOut,
        void			*data)
 {
        ...
 }

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

 void
 CTestTexture::vtx_Cleanup (
         void			*data)
 {
        ...
 }

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

        LXtItemType
 CTestTexture::MyType ()
 {
        ...
 }

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

 LXtItemType
 CTestTexture::MyType ()
 {
       ...
 }

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_Enabled (
        const char		*channelName,
        ILxUnknownID		 msg,
        ILxUnknownID		 item,
        ILxUnknownID		 read)
 {
        ...
 }

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.

 LxResult
 CTestTexture::cui_DependencyCount (
        const char		*channelName,
        unsigned		*count)
 {
       ...
 }
 
        LxResult
 CTestTexture::cui_DependencyByIndex (
        const char		*channelName,
        unsigned		 index,
        LXtItemType		*depItemType,
        const char	       **depChannelName)
 {
       ...
 }