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Index › Programming Questions & Help › OpenGL and 3D Libraries › Texture in 'pure' openGL
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Texture in 'pure' openGL (Read 7307 times)
triscuit
Re: Texture in 'pure' openGL
Reply #15 - May 3rd, 2008, 2:17am  
Strangely enough I was able to alter the code to make it transparent.

It's not perfect because I think only the outside is transparent but it's still a cool effect. If anyone knows how to fix it that would be great.

http://www.tristanhansen.com/texture_test3.pde
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julapy
Re: Texture in 'pure' openGL
Reply #16 - May 3rd, 2008, 11:12am  
if the ByteBuffer includes an alpha channel you must specify this the glTexImage2D call.

just change GL.GL_RGB to GL.GL_RGBA

gl.glTexImage2D(GL.GL_TEXTURE_2D, 0, GL.GL_RGBA, img.width, img.height, 0, GL.GL_RGBA, GL.GL_UNSIGNED_BYTE, getTextureByteBuffer( true ) );
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triscuit
Re: Texture in 'pure' openGL
Reply #17 - May 3rd, 2008, 10:47pm  
julapy wrote on May 3rd, 2008, 11:12am:
if the ByteBuffer includes an alpha channel you must specify this the glTexImage2D call.

just change GL.GL_RGB to GL.GL_RGBA

gl.glTexImage2D(GL.GL_TEXTURE_2D, 0, GL.GL_RGBA, img.width, img.height, 0, GL.GL_RGBA, GL.GL_UNSIGNED_BYTE, getTextureByteBuffer( true ) );


Oh I get it. That lets me use the transparency of the png.

Thanks,

I'm guessing there is no way to control the amount of transparency.
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triscuit
Re: Texture in 'pure' openGL
Reply #18 - May 4th, 2008, 12:30pm  
Any ideas on how I can pass an array to the pixels on the texture?
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« Last Edit: May 4th, 2008, 7:16pm by triscuit »  
 
pdinnen
Re: Texture in 'pure' openGL
Reply #19 - Nov 23rd, 2008, 6:06pm  
Just a note for other OpenGL newbies like myself. I was using Julapy's excellent code (http://www.julapy.com/processing/TextureTest.pde) but getting a weird effect where my my texture was being applied with a diagonal break.

I discovered that OpenGL textures need to be sized in powers of two (2,4,8,16...) so I resized the texture JPG to 256x256 and it works great. That came from a useful tutorial on OpenGL textures at http://www.gamedev.net/reference/articles/article947.asp
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