Visual Studio Fallback error - Programming C++

Question

I have some code I am trying to run on my laptop, but it keeps giving a 'FALLBACK' error. I don't know what it is, but it is quite annoying. It should just print 'Hello world!', but it prints it twice and changes the colours a little bit.

The same code is running perfectly on my PC.

I've searched a long time to solve this problem, but couldn't find anything. I hope some people out here can help me?

Here is my code:

// Template, major revision 3

#include "string.h"
#include "surface.h"
#include "stdlib.h"
#include "template.h"
#include "game.h"

using namespace Tmpl8;

void Game::Init()
{
    // put your initialization code here; will be executed once
}

void Game::Tick( float a_DT )
{
    m_Screen->Clear( 0 );
    m_Screen->Print( "hello world", 2, 2, 0xffffff );
    m_Screen->Line( 2, 10, 66, 10, 0xffffff );
}

Thanks in advance! :-)

Edit:

It gives an error on this line:

glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, SCRWIDTH, SCRHEIGHT, 0, GL_BGRA, GL_UNSIGNED_BYTE, NULL );

Maybe this could help?

Answer 1

Looking at this post from OpenGl Forums and seeing that you're using OpenGL, I may have an idea. You say that the code works fine on your computer but not on your notebook. There you have a possible hardware (different video cards) and software (different OpenGL version/support).

What may be happening is that the feature you want to use from OpenGL is not supported on your notebook. Also, you are creating a texture without data (the NULL on the last parameter), this will probably give you errors such as buffer overflow.

EDIT:

You may take a look on GLEW. It has a tool called "glewinfo" that looks for all features available on your hardware/driver. It generates a file by the same name on the same path of the executable. For the power of two textures, look for GL_ARB_texture_non_power_of_two.

EDIT 2:

As you said on the comments, without the GL_ARB_texture_non_power_of_two extension, and the texture having size of 640x480, glTexture will give you an error, and all the code that depends on it will likely fail. To fix it, you have to stretch the dimensions of the image to the next power of two. In this case, it would become 1024x512. Remember that the data that you supply to glTexture MUST have these dimensions.

Answer 2

Seeing that the error comes from the line:

glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, SCRWIDTH, SCRHEIGHT, 0, GL_BGRA, GL_UNSIGNED_BYTE, NULL );

Here are the reasons why that function could return GL_INVALID_VALUE. Since I can't check it for sure, you'll have to go through this list and make sure which one of them caused this issue.

GL_INVALID_VALUE is generated if level is less than 0.

GL_INVALID_VALUE may be generated if level is greater than log 2 ⁡ max , where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if internalFormat is not 1, 2, 3, 4, or one of the accepted resolution and format symbolic constants.

GL_INVALID_VALUE is generated if width or height is less than 0 or greater than 2 + GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if non-power-of-two textures are not supported and the width or height cannot be represented as 2 k + 2 ⁡ border for some integer value of k.

GL_INVALID_VALUE is generated if border is not 0 or 1.

EDIT: I believe it could be the non-power-of-two texture size that's causing the problem. Rounding your texture size to the nearest power-of-two should probably fix the issue.

EDIT2: To test which of these is causing an issue, let's start with the most common issue; trying to create a texture of non-power-of-two size. Create an image of size 256x256 and call this function with 256 for width and height. If the function still fails I would try putting the level to 0 (keeping the power-of-two size still in place).

BUT DANG you don't have data for your image? It's set as NULL. You need to load the image data into memory and pass it to the function to create the texture. And you aren't doing that. Read how to load images from a file or how to render to texture, whichever is relevant to you.

Answer 3

This is to give you a better answer as a fresh post. First you need this helper function to load a bmp file into memory.

unsigned int LoadTex(string Image)
{
    unsigned int Texture;

                FILE* img = NULL;
                img = fopen(Image.c_str(),"rb");

    unsigned long bWidth = 0;   
    unsigned long bHeight = 0;  
    DWORD size = 0; 

    fseek(img,18,SEEK_SET);
    fread(&bWidth,4,1,img);
    fread(&bHeight,4,1,img);
    fseek(img,0,SEEK_END);
    size = ftell(img.file) - 54;

    unsigned char *data = (unsigned char*)malloc(size);

    fseek(img,54,SEEK_SET); // image data
    fread(data,size,1,img);

    fclose(img);

    glGenTextures(1, &Texture);
    glBindTexture(GL_TEXTURE_2D, Texture);
    gluBuild2DMipmaps(GL_TEXTURE_2D, 3, bWidth, bHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, data);

    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

    if (data)
        free(data);

    return Texture;
}

Courtesy: Post by b0x in Game Deception.

Then you need to call it in your code likewise:

unsigned int texture = LoadTex("example_tex.bmp");