09-14-2023, 10:58 PM
Here are a couple of tutorial programs I have created so far. Please let me know if you notice something wrong in either of them.
Code: (Select All)
OPTION _EXPLICIT
' Example 1
' Hardware image persistance and display order
DIM SoftwareBox AS LONG ' software image
DIM HardwareBox AS LONG ' hardware image
DIM TempBox AS LONG ' temporary image to draw other images
DIM Count AS INTEGER ' generic counter
DIM x AS INTEGER ' location of images on screen
DIM dir AS INTEGER ' direction of images on screen
SCREEN _NEWIMAGE(640, 480, 32) ' create the main screen (software surface)
'+-------------------------------------------------------------------------------------------------------------------------+
'| Create two 320x200 images, one a software image, the other a hardware image |
'+-------------------------------------------------------------------------------------------------------------------------+
TempBox = _NEWIMAGE(320, 200, 32) ' create a temporary software image
_DEST TempBox ' draw on the temporary image
CLS , _RGB32(0, 0, 255) ' clear it with a blue background
COLOR _RGB32(255, 255, 0), _RGB32(0, 0, 255) ' set text color to yellow on blue
LOCATE 2, 1 ' position cursor
FOR Count = 1 TO 40 ' print 40 times on temporary image
PRINT " Software "; ' print the word
NEXT Count
LINE (0, 0)-(319, 199), _RGB32(255, 255, 0), B ' put a yellow border around the image
SoftwareBox = _COPYIMAGE(TempBox, 32) ' copy temporary software image to a software image (notice the 32)
LOCATE 2, 1 ' reposition cursor
FOR Count = 1 TO 40 ' print 40 times on temporary image
PRINT " Hardware "; ' print the word
NEXT Count
LINE (0, 0)-(319, 199), _RGB32(255, 255, 0), B ' redraw the yellow border
HardwareBox = _COPYIMAGE(TempBox, 33) ' copy temporary software image to a hardware image (notice the 33)
_DEST 0 ' go back to drawing on the main screen
_FREEIMAGE TempBox ' temporary image no longer needed
'+-------------------------------------------------------------------------------------------------------------------------+
'| The display order of software and hardware images can be set using the _DISPLAYORDER statement. The default display |
'| order is to draw software images first and then hardware images second. This has the effect of drawing software images |
'| in the background (UNDER) and hardware images in the foreground (OVER). Basically, the last surface identified using |
'| _DISPLAYORDER will have its images on top of all other surfaces. |
'+-------------------------------------------------------------------------------------------------------------------------+
'+-------------------------------------------------------------------------------------------------------------------------+
'| Enable the following line for the default display order |
'+-------------------------------------------------------------------------------------------------------------------------+
_DISPLAYORDER _SOFTWARE , _HARDWARE ' HARDWARE images will appear ON TOP of SOFTWARE images (this is default)
'+-------------------------------------------------------------------------------------------------------------------------+
'| Enable the following line to reverse the default display order (disable the line above) |
'+-------------------------------------------------------------------------------------------------------------------------+
'_DISPLAYORDER _HARDWARE , _SOFTWARE ' SOFTWARE images will appear ON TOP of HARDWARE images
x = 0 ' set x location of software image
dir = 1 ' set movement direction of software image
DO
_LIMIT 30
'+---------------------------------------------------------------------------------------------------------------------+
'| You'll notice that the software image is leaving a trail of yellow behind it (artifacts) while the hardware is not. |
'| The hardware surface will automatically move a hardware image from one location to another without leaving any sign |
'| where the image previously was. A "self-cleaning" method so to speak because the GPU discards the image immediatly. |
'| The software surface does not have this "self-cleaning" ability and therefore must be maintained by the programmer |
'| to keep artifacting from happening. A simple CLS statement will accomplish this. |
'+---------------------------------------------------------------------------------------------------------------------+
' +-----------------------------------------------------------------------------------------------------------------+
'CLS '| Enable this line of code to keep the software image from artifacting |
' +-----------------------------------------------------------------------------------------------------------------+
'+---------------------------------------------------------------------------------------------------------------------+
'| Notice that when you activated the CLS statement above the software image now begins to flicker too. The _DISPLAY |
'| statement explained below will clear this up as well. |
'+---------------------------------------------------------------------------------------------------------------------+
x = x + dir ' a few lines of code to keep the images moving back and forth
IF x = 320 OR x = 0 THEN dir = -dir
_PUTIMAGE (x, 100), SoftwareBox ' the software surface is persistant
_PUTIMAGE (320 - x, 179), HardwareBox ' the hardware surface is NOT persistant
'+---------------------------------------------------------------------------------------------------------------------+
'| You'll notice the hardware image is flickering. This is because the hardware surface will automatically clear |
'| itself. _DISPLAY must be used in order to retain hardware images until the next screen update. |
'| Remove the remark from the line below to see that the flickering has disappeared. |
'+---------------------------------------------------------------------------------------------------------------------+
' +-----------------------------------------------------------------------------------------------------------+
'_DISPLAY ' | Enable this line to continuing showing hardware images between screen updates |
' +-----------------------------------------------------------------------------------------------------------+
'+---------------------------------------------------------------------------------------------------------------------+
'| When the _DISPLAY statement above is active all drawing events to the screen are held in a queue. When the code |
'| reaches the _DISPLAY statement all drawing events are performed at once. This keeps multiple hardware images from |
'| disappearing on the hardware surface during drawing. See HWLesson2.BAS to see an example. |
'+---------------------------------------------------------------------------------------------------------------------+
LOOP UNTIL _KEYDOWN(27) ' exit when the ESC key is pressedCode: (Select All)
OPTION _EXPLICIT
' Example 2
' Software surface vs hardware surface
DIM HardwareBox AS LONG ' hardware image
DIM SoftwareBox AS LONG ' software image
DIM TempBox AS LONG ' temporary image to draw other images
DIM Count AS INTEGER ' generic counter
SCREEN _NEWIMAGE(640, 480, 32) ' create the main screen (software surface)
'+-------------------------------------------------------------------------------------------------------------------------+
'| Create two 320x200 images, one a software image, the other a hardware image |
'+-------------------------------------------------------------------------------------------------------------------------+
TempBox = _NEWIMAGE(320, 200, 32) ' create a temporary software image
_DEST TempBox ' draw on the temporary image
CLS , _RGB32(0, 0, 255) ' clear it with a blue background
COLOR _RGB32(255, 255, 0), _RGB32(0, 0, 255) ' set text color to yellow on blue
LOCATE 2, 1 ' position cursor
FOR Count = 1 TO 40 ' print 40 times on temporary image
PRINT " Software "; ' print the word
NEXT Count
LINE (0, 0)-(319, 199), _RGB32(255, 255, 0), B ' put a yellow border around the image
SoftwareBox = _COPYIMAGE(TempBox, 32) ' copy temporary software image to a software image (notice the 32)
LOCATE 2, 1 ' reposition cursor
FOR Count = 1 TO 40 ' print 40 times on temporary image
PRINT " Hardware "; ' print the word
NEXT Count
LINE (0, 0)-(319, 199), _RGB32(255, 255, 0), B ' redraw the yellow border
HardwareBox = _COPYIMAGE(TempBox, 33) ' copy temporary software image to a hardware image (notice the 33)
_DEST 0 ' go back to drawing on the main screen
_FREEIMAGE TempBox ' temporary image no longer needed
'+------------------------------------------------------------+
'| Draw three software images to the software surface outside |
'| of a loop. Remember that the SCREEN is the software |
'| surface. The software surface is maintained by the CPU and |
'| QB64 itself through underlying code. |
'+------------------------------------------------------------+
PRINT " 3 Software images drawn 1/10th of a second apart"
_PUTIMAGE (0, 20), SoftwareBox ' draw software images to the software surface (the SCREEN)
_DELAY .1
_PUTIMAGE (159, 139), SoftwareBox
_DELAY .1
_PUTIMAGE (319, 259), SoftwareBox
_DELAY .1
LOCATE 24, 2: PRINT "Once a software image is drawn"
LOCATE 25, 2: PRINT "it persitently stays on the screen"
LOCATE 26, 2: PRINT "with no updating or redrawing needed."
LOCATE 28, 2: PRINT "Hardware images next, press a key..."
SLEEP
CLS
'+------------------------------------------------------------+
'| Draw three hardware images to the hardware surface outside |
'| of a loop. Remember that hardware images have their own |
'| hardware surface completely independent from the software |
'| surface. The hardware surface is maintained by the GPU. |
'+------------------------------------------------------------+
PRINT " 3 Hardware images drawn 1/10th of a second apart"
_PUTIMAGE (0, 20), HardwareBox ' draw hardware images to the hardware surface in the GPU
_DELAY .1
_PUTIMAGE (159, 139), HardwareBox
_DELAY .1
_PUTIMAGE (319, 259), HardwareBox
_DELAY 1.1
LOCATE 24, 2: PRINT "Where are they?"
SLEEP 2
LOCATE 25, 2: PRINT "Hardware images are maintained by the"
LOCATE 26, 2: PRINT "GPU. They are displayed and then discarded."
LOCATE 28, 2: PRINT "Press a key...."
SLEEP
'+------------------------------------------------------------+
'| Draw three hardware images to the hardware surface inside |
'| of a loop. The _DISPLAY statement needs to be used to |
'| queue the images. Without the _DISPLAY statement in the |
'| loop below the hardware images will flicker because the |
'| GPU will remove them immediatly after they are drawn. |
'+------------------------------------------------------------+
CLS
PRINT " 3 Hardware images drawn using a queue"
LOCATE 24, 2: PRINT "You need to queue them up using"
LOCATE 25, 2: PRINT "_DISPLAY inside of a loop after"
LOCATE 26, 2: PRINT "all the images have been drawn."
LOCATE 28, 2: PRINT "Press ESC to exit...."
DO
_LIMIT 15 ' limit CPU to keep from overheating
_PUTIMAGE (0, 20), HardwareBox ' draw hardware images to the _DISPLAY queue
_PUTIMAGE (159, 139), HardwareBox
_PUTIMAGE (319, 259), HardwareBox
'+--------------------------------------------------------+
'| Disable the _DISPLAY statement below to see the |
'| flickering mentioned above. |
'+--------------------------------------------------------+
_DISPLAY ' dump hardware images to the GPU, software images to the SCREEN
LOOP UNTIL _KEYDOWN(27)
'+------------------------------------------------------------+
'| When we leave the loop there is nothing refreshing the |
'| hardware surface so the GPU instantly clears the images. |
'+------------------------------------------------------------+
_AUTODISPLAY
LOCATE 16, 8: PRINT "Notice how the hardware images disappeared when we left the loop."
LOCATE 18, 5: PRINT "Remember that hardware images are not persistent and will be discarded."
SLEEP 2
END