Texture test¶
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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | 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.
1 2 3 4 5 | LXtTagInfoDesc CTestTexture::descInfo[] = {
{ LXsSRV_USERNAME, "Test Value Texture" },
{ LXsSRV_LOGSUBSYSTEM, "val-texture" },
{ 0 }
};
|
./Initialize_(index)¶
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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | #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 Package_(lx-package.hpp)#.2815.29_SDK:_ILxAddChannel_interface method 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 Action_(lx-action.hpp)#.2822.29_User_Class:_Evaluation_method 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 value andor color at the current shading spot using cached values. This is the core of the texture value plugin, the place where actual values are computed and passed down to the texture engine. The role of the texture plugin is to set tOut->value, this value is then applied as a texture effect.
For example if the texture effect is ‘displacement’, the value will be transformed into a displacement distance by multiplying the value by the displacement amplitude. This is not the job of texture value plugin however, all the texture needs to do is provide the value (between 0 and 1).
For color effects, the texture can either set the color indirectly by setting a value that interpolates the 2 base colors, or directly by setting the color (tOut->color[0]) and setting tOut->direct to 1. Most procedural textures use the first method: they compute a value and that interpolates 2 base colors (tOut->color[0], tOut->color[1]), but other textures such as image maps set the color directly because the result of their computation is a color.
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 LXa_SCENESERVICE_(index)#Item_Types 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.
1 2 3 4 5 6 7 8 9 | 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)
{
...
}