Ive already posted this question, but it did not get any usefull answers. I'm trying to create two textures in OpenGL. Initially i did it like this:
unsigned int texture1, texture2;
glGenTextures(1, &texture1);
glBindTexture(GL_TEXTURE_2D, texture1);
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_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(true);
unsigned char *data = stbi_load("C:\\Users\\A\\Desktop\\wall.jpg", &width, &height, &nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
glGenTextures(1, &texture2);
glBindTexture(GL_TEXTURE_2D, texture2);
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_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
data = stbi_load("C:\\Users\\A\\Desktop\\awesomeface.png", &width, &height, &nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
This code works perfectly fine and runs with no visible issues. Obviously building these textures are the exact same procces both times, and so i figured I would use a for loop instead:
unsigned int textures[2];
int width, height, nrChannels;
unsigned char *data = stbi_load("C:\\Users\\A\\Desktop\\wall.jpg", &width, &height, &nrChannels, 0);
glGenTextures(2, textures);
for (int i = 0; i < 2; i++)
{
if (i == 1)
{
stbi_image_free(data);
data = stbi_load("C:\\Users\\A\\Desktop\\awesomeface.png", &width, &height, &nrChannels, 0);
}
glBindTexture(GL_TEXTURE_2D, (i == 0) ? textures[0] : textures[1]);
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_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, (i = 0) ? GL_RGB : GL_RGBA, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture!" << std::endl;
}
}
But this code breaks completely with the error: Unhandled exception at 0x03C78893 (ig9icd32.dll) in LearnOpenGL.exe: 0xC0000005: Access violation reading location 0x0A47B000.
I am sure you can point out lots of things that you dont like about the code, or stuff that maybe could become a problem later on, but seeing as i really just want an answer for this specific problem, please dont post an answer unless you have something that will actually make this code compile.
The expression (i = 0)
is an assignment in
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, (i = 0) ? GL_RGB : GL_RGBA, GL_UNSIGNED_BYTE, data);
This causes that the control variable i
of the for
loop, is continuously set to 0 and the loop never terminates.
You have to use the compare operator ==
instead of the assignment operator =
:
(i == 0) ? GL_RGB : GL_RGBA
Note, the expression
(i = 0) ? GL_RGB : GL_RGBA
is evaluated as
0 ? GL_RGB : GL_RGBA
which results in
GL_RGBA
The first image is an image with 3 color channels, but because of the wrong operator you try to read 4 color channels and access the data
buffer out of bounds. This causes the access violation when reading the data:
0xC0000005: Access violation reading location 0x0A47B000.
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