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Re: from NSImage to a Texture
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Re: from NSImage to a Texture

Nope, this works. I have that also on the to do list. OS projects
have hampered the sample code production in recent months hopefully we
can get more out soon.

On Sep 30, 2003, at 5:20 PM, Chuck Soper wrote:

> First, this list has been very helpful to me and I'm glad to hear that
> more samples are in the works. A Cocoa/Objective-C version of the
> OpenGL Image sample would be very helpful to me so that I can better
> understand generating multiple textures from an image. The current
> OpenGL Image uses Carbon/C.
> Thanks, Chuck
> P.S. I understand that isn't the right channel for requests. Should I
> file a feature request somewhere?
>
> At 10:22 AM -0600 9/29/03, Geoff Stahl wrote:
>> Use Kent's stuff or you can look at the "Cocoa OpenGL" sample as is
>> uses a NSImage of a string and goes to a texture in its string texture
>> class. See <http://developer.apple.com/opengl> for a link to the
>> sample.
>>
>> On the list to do is a better sample that shows exactly what you are
>> looking for.
>>
>> On Sep 28, 2003, at 7:20 PM, Kent Miller wrote:
>>
>>> On Sunday, September 28, 2003, at 12:00 AM,
>>> email@hidden wrote:
>>>> Alright, ive gone throught the sample code (OpenGL Image) and im
>>>> upto
>>>> the 'load an image into an NSImage ' stage. now what ? how do i
>>>> get
>>>> the info i need from the NSImage into a texture to use in OpenGL ?
>>>> I had asked a similar question sometime back and i got responses
>>>> asking me to check out NSImage and NSImageRep and the 'OpenGL
>>>> Image'
>>>> sample code. i've looked around at tutorials and im still unclear
>>>> on
>>>> how to get from an NSImage to a texture that i can use in OpenGL.
>>>> please help :).
>>>>
>>>
>>> Someone may have a better version but this ought to get you started:
>>>
>>>
>>> static unsigned int truncPowerOf2(unsigned int x)
>>> {
>>> int i = 0;
>>> while (x = x>>1) i++;
>>> return (1<<i);
>>> }
>>>
>>>
>>> void TextureFromNSImage(NSImage *image, GLuint *texID, GLuint *
>>> width,GLuint *height)
>>> {
>>> NSBitmapImageRep *sourceImageRep;
>>> GLenum imageFormat = GL_RGBA;
>>> GLubyte *sourcePic;
>>> long sourceRowBytes, pixelSize;
>>> NSSize imageSize;
>>>
>>> sourceImageRep = [[NSBitmapImageRep alloc]initWithData: [image
>>> TIFFRepresentation]];
>>>
>>> if ([sourceImageRep hasAlpha] == YES)
>>> {
>>> if ([sourceImageRep bitsPerPixel] != 32) return;
>>> imageFormat = GL_RGBA;
>>> pixelSize = 4;
>>> }
>>> else
>>> {
>>> if ([sourceImageRep bitsPerPixel] != 24) return;
>>> imageFormat = GL_RGB;
>>> pixelSize = 3;
>>> }
>>>
>>> sourceRowBytes = [sourceImageRep bytesPerRow];
>>> sourcePic = (GLubyte*) [sourceImageRep bitmapData];
>>> imageSize = [sourceImageRep size];
>>>
>>> //Do the OpenGL flip
>> > {
>> > GLubyte *pic = malloc( imageSize.height * sourceRowBytes );
>> > GLuint i;
>> >
>> > for (i = 0; i < imageSize.height; i++)
>> > {
>> > memcpy ( pic + (i * sourceRowBytes),
>>> sourcePic + ((((int)imageSize.height - i) - 1) *
>>> sourceRowBytes),
>>> sourceRowBytes);
>>> }
>>> sourcePic = pic;
>>> }
>>>
>>> glPixelStorei(GL_UNPACK_ROW_LENGTH, sourceRowBytes/pixelSize);
>>> glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
>>>
>>> if (*texID == 0)
>>> glGenTextures(1, texID);
>>> glBindTexture(GL_TEXTURE_2D,*texID);
>>>
>>> *width = truncPowerOf2(imageSize.width);
>>> *height = truncPowerOf2(imageSize.height);
>>>
>>> glTexImage2D(GL_TEXTURE_2D, 0, imageFormat, *width, *height, 0,
>>> imageFormat, GL_UNSIGNED_BYTE, sourcePic);
>>>
>>> [sourceImageRep release];
>>> }
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>>>
>>>
>> ---
>> Geoff Stahl
>> 3D Software Engineer
>> Apple
>> _______________________________________________
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> _______________________________________________
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> Help/Unsubscribe/Archives:
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> Do not post admin requests to the list. They will be ignored.
>
>
---
Geoff Stahl
3D Software Engineer
Apple
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References: 
 >Re: from NSImage to a Texture (From: Kent Miller <email@hidden>)
 >Re: from NSImage to a Texture (From: Geoff Stahl <email@hidden>)
 >Re: from NSImage to a Texture (From: Chuck Soper <email@hidden>)



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