Core Scene Graph Data Structures in C++
PixelTexture and ImageTexture
In the VRML’97 Standard the texture field of an Appearance node is allowed to contain pointers to several different texture nodes. In the DGP2023 implementation the texture field of an Appearance node is only allowed to contain a pointer to an ImageTexture node, which is implemented as a subclass of the PixelTexture node, or to directly to a PixelTexture node.
The TextureTransform node is not implemented as a class in the DGP2023 application, and the Appearance class does not contain a field to store a pointer to an instance of a TextureTransform node. Along the same lines, the DGP2023 application does not yet include a class to represent images. In the DGP2023 data structures the PixelTexture node is implemented as a separate class just because it make sense to make ImageTexture a subclass of PixelTexture, but the functionality needed to manipulate images and pixels is not implemented yet. This functionality will be added as the need arises later.
This is how the PixelTexture node and the ImageTexture node are defined in the VRML'97 Standard.
PixelTexture {
// SFImage image 0 0 0
SFBool repeatS TRUE
SFBool repeatT TRUE
}
ImageTexture {
MFString url []
SFBool repeatS TRUE
SFBool repeatT TRUE
}
This are the public interfaces to the PixelTexture class and to the ImageTexture class, as defined in the DGP2023 implementation.
class PixelTexture : public Node {
public:
PixelTexture();
virtual ~PixelTexture();
bool getRepeatS();
bool getRepeatT();
void setRepeatS(bool value);
void setRepeatT(bool value);
virtual bool isPixelTexture() const { return true; }
virtual string getType() const { return "PixelTexture"; }
};
class ImageTexture : public PixelTexture {
public:
ImageTexture();
virtual ~ImageTexture();
vector<string>& getUrl();
string getUrl(int i);
void adToUrl(const string& str);
virtual bool isImageTexture() const { return true; }
virtual string getType() const { return "ImageTexture"; }
};