hello ,
i am a newbie in opengl but i have given a difficult task of creating an ray cast application for which i need to pass 4- 5 textures to my glsl shaders. i have 2 issues
ISSUE 1)
when i pass textures to my shaders like this , i get the output image on my screen
texture_locationTemp = glGetUniformLocation(p2, "temporarytexture");
glUniform1i(texture_locationTemp, 1);
texture_locationVol = glGetUniformLocation(p2, "VolumeTexture");
glUniform1i(texture_locationVol, 2);
texture_locationDir = glGetUniformLocation(p2, "Directiontexture");
glUniform1i(texture_locationDir,3);
glActiveTexture([b]GL_TEXTURE1[/b]);
glBindTexture(GL_TEXTURE_2D, swapLogic[ 1- currentSurface]);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_3D, Volumetex3d);
glActiveTexture(GL_TEXTURE3);
glBindTexture(GL_TEXTURE_2D, texIDBack);
But when i pass textures like this (Starting from location GL_TEXTURE0 instead of GL_TEXTURE1), i get the distored image.
texture_locationTemp = glGetUniformLocation(p2, “temporarytexture”);
glUniform1i(texture_locationTemp, 0);
texture_locationVol = glGetUniformLocation(p2, “VolumeTexture”);
glUniform1i(texture_locationVol, 1);
texture_locationDir = glGetUniformLocation(p2, “Directiontexture”);
glUniform1i(texture_locationDir,2);
glActiveTexture([b]GL_TEXTURE0[/b]);
glBindTexture(GL_TEXTURE_2D, swapLogic[ 1- currentSurface]);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_3D, Volumetex3d);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, texIDBack);
i am not able to understand this starange behavior , seems like
GL_TEXTURE0 does not work.
ISSUE 2)
ISSUE 2 is related to issue 1)
in the beginning before starting rendering ( before onpaint method),
i m creating 7-8 2d textures and 1-2 3d textures which i will pass further to my shaders during final rendering step… and this code is executed only once during execution…
Gluint Volumetex3d = textureHandlerObj.Create3DTexture(path,rawdata);
Gluint texIDEmptySpaceTexture = Create3DTextureEmptyScpaceTexture();
Gluint crop2dTex = Create2DTexture(viewPort.width,viewPort.height);
Gluint texIDBack = Create2DTexture(viewPort.width,viewPort.height);
Gluint texIDfront = Create2DTexture(viewPort.width,viewPort.height);
…
…
the issue is that if i change the order of creation of these textures, the output on my screen changes…
for instance if i change the order to
Gluint Volumetex3d = textureHandlerObj.Create3DTexture(path,rawdata);
Gluint texIDEmptySpaceTexture = Create3DTextureEmptyScpaceTexture();
Gluint crop2dTex = Create2DTexture(viewPort.width,viewPort.height);
[b]Gluint texIDfront = Create2DTexture(viewPort.width,viewPort.height);
Gluint texIDBack = Create2DTexture(viewPort.width,viewPort.height);[/b]
now texidFront is created before textureIdBack…
code inside all this functions like similar to this ( using GL_TEXTURE_2D for 2d texture and GL_TEXTURE_3D for 3d texture)…
GLuint img;
glGenTextures(1, &img);
glBindTexture(GL_TEXTURE_2D, img);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, width, height, 0, GL_RGBA, GL_FLOAT, data);
i dont understand why order of creation of this textures effect my output…
what i think can be a bug is
if i use the order no 1 then the the texture binded to GL_TEXTURE_2D after the end of the function is texIdfront but if i use order no 2 then it is texIdBack …
i think this binding switch is somewhere casuing the problem due to which these textures are not passed to shaders properly which cause the distortion.
but i m not able to find out what i am missing and what i have to do to make it work for any order ( why it deopends upon order)…
PLZ HELP … 
