Print Page - Nehe Lesson 6 with transparent images (DevIL question)

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: baegsi on January 24, 2005, 13:25:36

I can't get the lwjgl-ported Nehe Lesson 6 with alpha transparency running :oops: .

This is the original code

..
IL.ilCopyPixels(0, 0, 0, 256, 256, 1, IL.IL_RGB, IL.IL_BYTE, scratch);
...
// Generate The Texture
GL11.glTexImage2D(
  GL11.GL_TEXTURE_2D,
  0, 
  GL11.GL_RGB, 
  IL.ilGetInteger(IL.IL_IMAGE_WIDTH),                   
  IL.ilGetInteger(IL.IL_IMAGE_HEIGHT), 
  0, 
  GL11.GL_RGB, 
  GL11.GL_UNSIGNED_BYTE, 
  scratch);
...

Now I just changed the format settings:

Code Select

...
IL.ilCopyPixels(0, 0, 0, 256, 256, 1, IL.IL_RGBA/*<==*/, IL.IL_BYTE, scratch);
...
// Generate The Texture
GL11.glTexImage2D(
  GL11.GL_TEXTURE_2D,
  0, 
  GL11.GL_RGBA, /*<==*/
  IL.ilGetInteger(IL.IL_IMAGE_WIDTH),                   
  IL.ilGetInteger(IL.IL_IMAGE_HEIGHT), 
  0, 
  GL11.GL_RGBA, /*<==*/
  GL11.GL_UNSIGNED_BYTE, 
  scratch);
...

and loaded the example with a png with transparency, but it crashes with an exception.
What do I wrong? Any help very appreciated!

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: baegsi on January 24, 2005, 13:36:22

Found the problem: "scratch" buffer too small. Instead of

QuoteByteBuffer scratch = ByteBuffer.allocateDirect(IL.ilGetInteger(IL.IL_IMAGE_WIDTH) * IL.ilGetInteger(IL.IL_IMAGE_HEIGHT) * 3);

I used:

QuoteByteBuffer scratch = ByteBuffer.allocateDirect(IL.ilGetInteger(IL.IL_IMAGE_WIDTH) * IL.ilGetInteger(IL.IL_IMAGE_HEIGHT) * 4 /*<==*/);

Hmh, I think I have to understand the whole xyBuffer stuff properly... :oops:

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: Matzon on January 24, 2005, 14:12:33

makes sense...
using RGB (no transparency) you use 3 Bytes per pixel (hence the 3) - adding the alpha channel (8 more bits, total 32) increases the size needed per pixel to 4 bytes.

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: K.I.L.E.R on January 26, 2005, 11:43:28

Why not just use this?

Code Select


ByteBuffer scratch = ByteBuffer.allocateDirect
        (
        		IL.ilGetInteger(IL.IL_IMAGE_BITS_PER_PIXEL) *
        		IL.ilGetInteger(IL.IL_IMAGE_DEPTH) *
        		IL.ilGetInteger(IL.IL_IMAGE_WIDTH) * 
        		IL.ilGetInteger(IL.IL_IMAGE_HEIGHT)
        );

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: CaptainJester on January 26, 2005, 12:15:41

Quote from: "K.I.L.E.R"Why not just use this?

Code Select Expand
ByteBuffer scratch = ByteBuffer.allocateDirect ( IL.ilGetInteger(IL.IL_IMAGE_BITS_PER_PIXEL) * IL.ilGetInteger(IL.IL_IMAGE_DEPTH) * IL.ilGetInteger(IL.IL_IMAGE_WIDTH) * IL.ilGetInteger(IL.IL_IMAGE_HEIGHT) );

You mean IL_IMAGE_BYTES_PER_PIXEL

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: K.I.L.E.R on January 26, 2005, 14:16:20

Quote from: "CaptainJester"
Quote from: "K.I.L.E.R"Why not just use this?

Code Select Expand
ByteBuffer scratch = ByteBuffer.allocateDirect ( IL.ilGetInteger(IL.IL_IMAGE_BITS_PER_PIXEL) * IL.ilGetInteger(IL.IL_IMAGE_DEPTH) * IL.ilGetInteger(IL.IL_IMAGE_WIDTH) * IL.ilGetInteger(IL.IL_IMAGE_HEIGHT) );

You mean IL_IMAGE_BYTES_PER_PIXEL

WHOOPS!
I'm an idiot. Sorry.

Title: Nehe Lesson 6 with transparent images (DevIL question)
Post by: baegsi on January 26, 2005, 20:01:22

Thanks, that's a better solution of course :)

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Programming => Lightweight Java Gaming Library => Topic started by: baegsi on January 24, 2005, 13:25:36