source: OGRE/trunk/ogrenew/Docs/manual/manual_52.html @ 657

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14<TITLE>OGRE Manual v1.0.7: Updating Pixel Buffers</TITLE>
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37<H3> 5.8.2 Updating Pixel Buffers </H3>
38<!--docid::SEC196::-->
39<P>
40
41Pixel Buffers can be updated in two different ways; a simple, convient way and a more difficult (but in some cases faster) method. Both methods make use of PixelBox objects (See section <A HREF="manual_55.html#SEC204">5.8.5 Pixel boxes</A>) to represent image data in memory.
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43
44<A NAME="SEC197"></A>
45<H3> blitFromMemory </H3>
46<!--docid::SEC197::-->
47<P>
48
49The easy method to get an image into a PixelBuffer is by using HardwarePixelBuffer::blitFromMemory. This takes a PixelBox object and does all necessary pixel format conversion and scaling for you. For example, to create a manual texture and load an image into it, all you have to do is
50</P><P>
51
52<TABLE><tr><td>&nbsp;</td><td class=example><pre>// Manually loads an image and puts the contents in a manually created texture
53Image img;
54img.load("elephant.png", "General");
55// Create RGB texture with 5 mipmaps
56TexturePtr tex = TextureManager::getSingleton().createManual(
57    "elephant",
58    "General",
59    TEX_TYPE_2D,
60    img.getWidth(), img.getHeight(),
61    5, PF_X8R8G8B8);
62// Copy face 0 mipmap 0 of the image to face 0 mipmap 0 of the texture.
63tex-&#62;getBuffer(0,0)-&#62;blitFromMemory(img.getPixelBox(0,0));
64</pre></td></tr></table></P><P>
65
66<A NAME="SEC198"></A>
67<H3> Direct memory locking </H3>
68<!--docid::SEC198::-->
69<P>
70
71A more advanced method to transfer image data from and to a PixelBuffer is to use locking. By locking a PixelBuffer
72you can directly access its contents in whatever the internal format of the buffer inside the GPU is.
73</P><P>
74
75<TABLE><tr><td>&nbsp;</td><td class=example><pre>/// Lock the buffer so we can write to it
76buffer-&#62;lock(HardwareBuffer::HBL_DISCARD);
77const PixelBox &#38;pb = buffer-&#62;getCurrentLock();
78
79/// Update the contents of pb here
80/// Image data starts at pb.data and has format pb.format
81/// Here we assume data.format is PF_X8R8G8B8 so we can address pixels as uint32.
82uint32 *data = static_cast&#60;uint32*&#62;(pb.data);
83size_t height = pb.getHeight();
84size_t width = pb.getWidth();
85size_t rowSkip = pb.getRowSkip(); // Skip between rows of image
86for(size_t y=0; y&#60;height; ++y)
87{
88    for(size_t x=0; x&#60;width; ++x)
89{
90        // 0xRRGGBB -&#62; fill the buffer with yellow pixels
91        data[rowSkip*y + x] = 0x00FFFF00;
92}
93}
94
95/// Unlock the buffer again (frees it for use by the GPU)
96buffer-&#62;unlock();
97</pre></td></tr></table></P><P>
98
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