Loading Texture

cloke

Unregistered

Post: #1

Aug 4, 2004 — 10:10 PM

I've been reading through the forums and Apples dev site, but I am stumped. I am trying to load an image using QT graphics import and then load the image as a GL texture. Below is my QT graphics importer. This works without an issue.

Code:

typedef struct {

        size_t width;

        size_t height;

        size_t bitsPerComponent;

        size_t bitsPerPixel;

        size_t bytesPerRow;

        size_t size;

        CGImageAlphaInfo ai;

        unsigned char *data;

    } BitmapInfo;

OSErr GetBitmapFileFromPStr( Str255 str, BitmapInfo *bi )

{

    FSSpec fss = ReadFile( str );

    OSErr  err;

    GraphicsImportComponent gi;

    err = GetGraphicsImporterForFile(&fss, &gi);

    readBitmapInfo(gi, bi);

    getBitmapData(gi, bi);

    CloseComponent(gi);

    return err;

}

The trouble I am having is then loading the image into a texture. I am really new with OpenGL so any help would be greatly appreciated. The code below is modified from NeHe, but I'm not sure what I am doing wrong.

Code:

    BitmapInfo      *TextureImage;

GLuint             texture;    

memset(TextureImage, 0, sizeof(void *)*2);

GetBitmapFileFromPStr( "\pFont.sgi", TextureImage );

glGenTextures(1, &texture);                    // Create The Texture

glBindTexture(GL_TEXTURE_2D, texture);

glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage->width, TextureImage->height, 0, 

GL_RGB, GL_UNSIGNED_BYTE, TextureImage->data);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

I'm not sure what I may be doing wrong.

OneSadCookie

Luminary

Posts: 5,125
Joined: 2002.04

Post: #2

Aug 5, 2004 — 04:27 AM

aside from the fact that that snippet is missing all the relevant code, why not search the forums? This question is answered at least twice a week...

FCCovett

Member

Posts: 156
Joined: 2002.11

Post: #3

Aug 5, 2004 — 09:05 AM

You may want to download the source code from http://www.angelfire.com/mac2/yexi/Basic...Struct.dmg

There, you will find a texture loader that works with JPG, PNG, or TGA.

cloke

Unregistered

Post: #4

Aug 9, 2004 — 08:44 PM

Thanks for the above link. I was able to take my code to create a CGImage and use the above code to pass that into a GL Texture. It's cool to be able to take any QT supported file format and create the GL texture from that.

FCCovett

Member

Posts: 156
Joined: 2002.11

Post: #5

Aug 10, 2004 — 12:50 AM

Just one thing: when creating the data buffer for the CGImage context, use calloc instead of malloc. Recently, I've tried to load some small PNG files and I was getting some noise because the buffer was not zeroed.

So, on LoadGLTextureFromCGImage():

Code:

//----------------------------------------------------------------------

    // Allocate memory block for bitmap buffer:

    data_buffer = (GLubyte *) calloc( bitmap_byteCount, sizeof( GLubyte ) );

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