Creating New Textures from Scratch¶
The PNMImage Class¶
This class is how Panda3D handles regular images (.gif, .jpg, and the like).
This class allows you to manipulate individual pixels of the image. You can load
existing images using the function
filename is the
path to the image file (in Panda Filename Syntax)
wrapped in a
Filename object. Or, you can create a brand new image from
scratch, by passing the x, y size to the constructor.
PNMImage my_image; my_image.read(Filename("testImg.png")); PNMImage my_empty_image(256, 256);
You can get the size of the image you have read using the
getYSize() functions. Although you cannot change the size of an image
directly, you can rescale an image by filtering it into a larger or smaller
PNMImage full_size(Filename("testImg.png")); PNMImage reduced(256, 256); reduced.gaussianFilterFrom(1.0, full_size);
You can get individual RGB values using the
getRed(x,y), getGreen(x,y), getBlue(x,y) or
getRedVal(x,y), getGreenVal(x,y), getBlueVal(x,y) where x and y tell what
pixel to look at (lower-left is 0,0 upper right is
getXSize()-1, getYSize()-1 The difference between these functions is that
get*Val functions return a number between 0 and 1 while the
functions return their value as an integer. For example, if your image uses
8-bit color calling
getGreenVal on a green pixel will return 255 and calling
getGreen will return 1. You can also get all the RGB information at the same
getXelVal(x,y) which return a 3-component
vector with red in the x, green in the y, and blue in the z.
# The pixel at 0,0 is red and we're using 8-bit color myImage.getRedVal(0,0) # Returns 255 myImage.getRed(0,0) # Returns 1 colors = myImage.getXelVal(0,0) # Returns (255,0,0) colorVal = myImage.getXel(0,0) # Returns (1,0,0)
The functions for setting pixel information are
setRed(x,y,value), setGreen(x,y, value), setBlue(x,y, value) or
setRedVal(x,y,value), setGreenVal(x,y, value), setBlueVal(x,y, value).
There is still the same dichotomy as above when it comes to regular sets and
using setvals. You can also use
setXelVal(x,y, colorVec). You can also fill an image with a color by using
myImage.setGreenVal(0, 0, 255) # If pixel (0,0) was red before, now it is yellow myImage.setBlue(0, 0, 1) # Pixel (0,0) is now white gray = Vec3(0.5, 0.5, 0.5) # Both of these set the origin to gray myImage.setXelVal(0, 0, gray * 255) myImage.setXel(0, 0, gray) # Makes every pixel red myImage.fillVal(255, 0, 0) # Makes every pixel green myImage.fill(0, 1, 0)
There are also gets and sets for the alpha channel using the same interface as
above. However, if you use them on an image that doesn’t have an alpha channel
you will cause a crash. To see if an image has an alpha channel use
hasAlpha() which returns True if there is an alpha channel and False
otherwise. You can add an alpha channel using
addAlpha(). You can also
remove it using
You can also make an image grayscale by using
makeGrayscale(). You can now
use sets and gets for Gray too. Using
getGray* on a color image just returns
the value in the blue channel. If you want to get the grayscale value of a pixel
regardless of whether the image is a grayscale or a color image, you can use
getBright(x,y), which works equally well on color or on grayscale images. If
you want to weight the colors use
getBright(x,y, r,g,b) where r,g,b are the
weights for their respective channels.
There are several other useful functions in the class, which are described on
PNMImage page in the API Reference.
Getting the Image of a Texture¶
Texture class does not allow for pixel manipulation. However the
PNMImage class below does. Therefore, if you want to change the image in a
Texture object you must call its
store(myImage) which saves the image of
the texture into
myImage = PNMImage() myTexture = loader.loadTexture("myTex.jpg") # After this call, myImage now holds the same image as the texture myTexture.store(myImage)
Loading a PNMImage Into a Texture¶
Once you have changed all the data in the image you can now load it into a
texture using the
load(myImage) function, where
myImage is the PNMImage to make the texture from.
// Assume we already have myImage which is our modified PNMImage PT(Texture) myTexture = new Texture("texture name"); // This texture now contains the data from myImage myTexture->load(myImage);
Remember however, that most graphics cards require that the dimensions of
texture have to be a power of two.
PNMImage does not have this restriction
and Panda will not automatically scale the image when you put it into a texture.