Textures and glsl

[Gabba123XXL]

I built a check image of 128x128. Black and white. The data which I bound is totally 128*128*3 bytes.

The data is arranged like row major data. But I don't think it is a problem with the image, I changed already to completely white but the result was still black.

I will check later the possibility if the shader produces the black fragments.

I guess, maybe I made a mistake in the initialization... Do you have any ideas, what could be wrong?

[Gabba123XXL]

Now I tested the LightIntensity... it was not the reason.
I think it is a problem with configuration.

[BionicBytes]

yo'll have to post code showing how you obtain the uniform location and how you send the uniform values.
eg your shader compilation and object rendering code.

[Gabba123XXL]

This is image creation:

for (unsigned int j=0; j<imgSize; ++j) {
	for (unsigned int i=0; i<imgSize; ++i) {
		if ( ((i+j) % tfs) < fs) {
			checkImage[i*3 + j*imgSize*3] = (GLubyte) 0;
			checkImage[(i+1)*3 + j*imgSize*3] = (GLubyte) 0;
			checkImage[(i+2)*3 + j*imgSize*3] = (GLubyte) 0;
		} else {
			checkImage[i*3 + j*imgSize*3] = (GLubyte) 255;
			checkImage[(i+1)*3 + j*imgSize*3] = (GLubyte) 255;
			checkImage[(i+2)*3 + j*imgSize*3] = (GLubyte) 255;
		}
	}
}

After that: Creation of the texture:

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(1, &_id);
glBindTexture(GL_TEXTURE_2D, _id);
 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 
glTexImage2D(GL_TEXTURE_2D,
	0,
	GL_RGB,
	128,
	128,
	0,
	GL_RGB,
	GL_UNSIGNED_BYTE,
	checkImage);
glBindTexture(GL_TEXTURE_2D ,0);

Now rendering: The shader program is in use

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, _id);
 
int texunit = 0;
GLint loc = glGetUniformLocation(program, "SampleTexture");
glUniform1iv(loc, uniform._count, (GLint*) &texunit);
 
// render

Here the details around the texels for the attribute...

glGenBuffers(1, &_buffers);
glBindBuffer(GL_ARRAY_BUFFER, _buffers);
GLfloat *texelBuffer = new GLfloat[texels.size()];
std::copy(texels.begin(), texels.end(), texelBuffer);
glBufferData(GL_ARRAY_BUFFER, texels.size()*sizeof(GLfloat), texelBuffer, GL_STATIC_DRAW);
glVertexAttribPointer((GLuint)3, 2, GL_FLOAT, GL_FALSE, 0, 0);
 
// At rendering time
glBindVertexArray(_vao);
...
glEnableVertexAttribArray(3);
glDrawElements(...)

That's it! Thanks a lot for your help.

[Gabba123XXL]

so any idea???

[Alfonse Reinheart]

glUniform1iv(loc, uniform._count, (GLint*) &texunit);

Several things.

1: Why are you uploading that as an array? It's not a sampler array; it's just a single sampler. Use `glUniform1i` instead.

2: Most important of all, did you call `glUseProgram(program)` before this? If not, then this call should generate a GL error (unless some other program was bound, in which case you likely did something really bad).

so any idea???

You waited a whole hour to bump the thread.

[Gabba123XXL]

First it doesn't matter if I load one single element to the uniform or an array of size one. Why I do it, has some decisions around my project which I am developing. Even I changed it in the case of one element using the simpler function 'glUniform1i' but the result is the same I have black geometries!

Most important of all, did you call `glUseProgram(program)` before this? If not, then this call should generate a GL error (unless some other program was bound, in which case you likely did something really bad).

Of course!!! If I wouldn't switch on the program then my whole scene would be black. I made a whole simple scene and T am using more than one shader program (by the way). The geometries which are affected by the texture shader are black, all others are rendered fine.

So far, did you see something what is wrong or in wrong order? What's about the glActiveTexture? Do I need 'glEnable(GL_TEXTURE)'?

[Gabba123XXL]

OK!
I fixed the problem. It was the "InternalFormat" and Format of "glTexImage". Both use the same flags but the types are different.
InternalFormat -> GLint
Format -> GLenum
My mistake was I sent nothing to internalFormat because my storage managment was a little bit confused!

Thank you for your help!

[Dark Photon]

It was the "InternalFormat" and Format of "glTexImage". Both use the same flags but the types are different.

No, they don't accept all the same flags (enumeration defines), but for legacy reasons there are a few enumeration defines that can be provided to both.

Format only specifies which components you're providing (if you're even providing data) for instance, GL_RED, GL_RGB, GL_RGBA, etc.

Whereas internal format typically specifies a precise internal format (including type and number of components and bits per component), for instance GL_R16F, GL_RGB8, GL_RGB10_A2, etc.

What sometimes is confusing is that you can provide "generic" formats such as GL_RGB to internal format and it tells OpenGL to just pick a specific internal format that it thinks is good enough for you.

Also regarding the types: In practice, internal format is a GLenum. However, I think the history on internal format being a GLint rather than a GLenum is that in days long ago you could provide 1, 2, 3, and 4 as internal formats and, again, that told OpenGL to just pick some format that it thinks may be good enough for you. Generally speaking, you should tell it precisely the one you want, with an specific internal format enum symbol (e.g. GL_RGB8).

[Gabba123XXL]

thank you... this helped me very much!