Image

Introduction

X3DToolKit manages images for different reasons. First of all, when a model has textures, the image textures have to be loaded before applied. Furthermore, a user can define images of its own, for example by copying the image buffer and then save in an appropriate format (compressed or not). The X3DTK::Image is made to be easy-use with OpenGL. To use the X3DTK::Image class, include <X3DTK/kernel.h>.

Using the Image class

You can use the Image class like this:

 // To load an image from file
 Image *image = new Image("file.jpg");
 // To get informations
 unsigned short width = image->getWidth();
 unsigned short height = image->getHeight();
 int pixelSize = image->getPixelSize();
 // To get the GL pixel format
 GLenum type = image->getGLType();
 // To get the data
 unsigned char *data = image->getData();

You can resize the image by two ways: You can specify new width and new height, or use it as an OpenGL texture.

 // Resizing to 800*600
 image->resize(800, 600);
 // Automatic resize for OpenGL. A texture transform is given to modify the OpenGL texture matrix.
 float textureTransform[16];
 image->resizeGL(textureTransform);

You can read pixels from the image:

 // unsigned byte RGB
 struct RGB_UB
 {
   unsigned char r;
   unsigned char g;
   unsigned char b;
 };
 // reading pixel x, y
 RGB_UB *p = Memory<RGB_UB>::access(image, x, y));
 p->r = 128;
 p->g = 32;
 p->b = 0;
 ...

You can create your own image:

 // Allocating a memory block.
 image->allocate(800, 600, GL_RGB, GL_FLOAT);
 // Reading pixels from image buffer.
 glReadPixels(0, 0, screenWidth, screenHeight, image->getGLFormat(), image->getGLType(), image->getData());

You can save the image:

 // Saving the image with quality 0.5
 image->saveAs("myfile.jpg", 0.5f);

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