Loading a cube map from existing textures in OpenGL
lazarus / 70-OpenGL

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soerensen3 · 2018-02-21 17:38

Dear All,

I'm trying to load an hdr cube map. For loading the radiance/hdr file
I'm using VampyreImagingOpenGL from trunk (The rest of the package is
the latest release because I couldn't get trunk working for me and the
release version of VampyreImagingOpenGL is converting hdr images to
8-bit before loading).
I want to load it into a cube map but it does not seem to work (I get
a black image).

Here is the relevant "pseudo" code:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i //For each
file...PX:= LoadGLTextureFromFile( path + 'PX.hdr'
);//...glGenTextures( 1, @GLTexture ); glBindTexture(
GL_TEXTURE_CUBE_MAP, GLTexture );//For each sideglBindTexture(
GL_TEXTURE_CUBE_MAP_POSITIVE_X, PX );//...glBindTexture(
GL_TEXTURE_CUBE_MAP, 0 ); 
From the OpenGL Documentation it says: QuoteWhen a texture is first
bound, it assumes the specified target: A texture first bound to
GL_TEXTURE_1D becomes one-dimensional texture, ...
(https://www.khronos.org/registry/OpenGL-
Refpages/gl4/html/glBindTexture.xhtml)
So my guess is that ImagingOpenGL initializes the texture as
GL_TEXTURE_2D.
Is there a simple way to copy/convert a texture to another? I'm of
course also open to other solutions. I'm trying to target OpenGL 2.1. 
Maybe glCopyTexImage2D is the solution but I'm not sure on how to use
it. What I tried is this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i //For each
file...PX:= LoadGLTextureFromFile( path + 'PX.hdr'
);//...glGenTextures( 1, @GLTexture );glBindTexture(
GL_TEXTURE_CUBE_MAP, GLTexture );//For each side...glBindTexture(
GL_TEXTURE_2D, PX ); glGetTexLevelParameteriv( GL_TEXTURE_2D, 0,
GL_TEXTURE_WIDTH, @Width ); glGetTexLevelParameteriv( GL_TEXTURE_2D,
0, GL_TEXTURE_HEIGHT, @Height ); glGetTexLevelParameteriv(
GL_TEXTURE_2D, 0, GL_TEXTURE_INTERNAL_FORMAT, @Internal
);glCopyTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, Internal, 0, 0,
Width, Height, 0 ); glDeleteTextures( 0, @PX );

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ChrisR · 2018-03-03 14:45

Not seeing all your code, it is hard to give advice. I think you want
to break this down into simpler questions if you want someone to
provide advice. For example, maybe you want to upload your source
image or a minimalistic project that illustrates your issue. The
current question is too vague to provide a solution.