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texture help

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ok I have made the code for building a house. Now when i try to put the textures onto it, it appears white, How do i make it fit the house when my textures have to 64 or 128 or 256 pixels?

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I''m not sure but I don''t think you have to have your textures in powers of 2. I think that if you use mipmapping you can bypass that little problem. But if you dont want to use mipmapping (I dont know why you wouldnt) then I''m pretty sure you can go above 256x256, you can use 512x512 or 1024x1024.

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Hmm, appearing white? Do you have any code that I can see? There are a couple of causes for a white texture (I am pretty sure its happened to me before) .. check and make sure you are enabling texturing in your program: glEnable(GL_TEXTURE_2D);

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ok i can give you some code, im sure i have the glEnable thing in there too. Heres the Code for the main section of the house.

glTexCoord2f(0.0f,1.0f); glVertex3f(-1.5f,1.0f,0.0f); glTexCoord2f(1.0f,1.0f); glVertex3f(2.0f,1.0f,0.0f);
glTexCoord2f(1.0f,0.0f); glVertex3f(2.0f,-1.0f,0.0f);
glTexCoord2f(0.0f,0.0f); glVertex3f(-1.5f,-1.0f,0.0f);

Hope you can help.

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That code seems OK, but I wouldn''t know as I havent seen your texture. Is there much white on the texture? You may be assigning the texture coordinates wrong but I doubt thats it

What about the initialization code?

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OpenGL normally only supports powers of two,
this is to get better performance as far as I know.

And as someone mentioned before, even it was in a
weird way, if you don''t use a function which resizes
the texture for you ( I think this meant as he said
when you use mipmapping, but it hasn''t to do anything
with mipmapping at all ).
Or 2nd option, you resize it manually so you haven''t to do
it while runtime.

gluBuild2DMipmaps() is the function which resizes the
texture for you and allows you to use mipmapping.

However if you don''t want to use mipmapping you could also use
this one gluScaleImage() to scale at runtime.

Hope this helped you!

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Guest Anonymous Poster
resize your texture to 256 x 256.

(needs to be a power of two for most hardware. thinking that latest nvidia boards support non-powers of two, but i don''t really know.)

make sure you create your textures after you have made an opengl context (after you''ve created the window is usually a safe point of reference, if you don''t know exactly when.)

by "creating textures" i mean glGenTex/glTexImage2d.

(i''m sure i''m screwing up the call names, but you get the idea.)

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Ok look obviusly your not loading the texture into memory using this function..

-------start from here with the copying---------

#define BITMAP_ID 0x4D42

//////Texture Information
unsigned char* bitmapData;
unsigned int texture;

unsigned char *LoadBitmapFile(char *filename, BITMAPINFOHEADER *bitmapInfoHeader)
FILE *filePtr;
unsigned char *bitmapImage;
int imageIdx = 0;
unsigned char tempRGB;

//open filename in "read binary" mode
filePtr = fopen(filename, "rb");
if(filePtr == NULL)
return NULL;

//read the bitmap file header
fread(&bitmapFileHeader, sizeof(BITMAPFILEHEADER), 1, filePtr);

//verify that this is a bitmap by checking for the universal bitmap id
if(bitmapFileHeader.bfType !=BITMAP_ID)
return NULL;

//read the bitmap information header
fread(bitmapInfoHeader, sizeof(BITMAPINFOHEADER), 1 ,filePtr);

//move file pointer to beginning of bitmap data
fseek(filePtr, bitmapFileHeader.bfOffBits, SEEK_SET);

//allocate enough memory for the bitmap image data
bitmapImage = (unsigned char*)malloc(bitmapInfoHeader->biSizeImage);

//verify memory allocation
if (!bitmapImage)
return NULL;

//read in the bitmap image data
fread(bitmapImage, 1, bitmapInfoHeader->biSizeImage, filePtr);

//make sure the bitmap date was read
if (bitmapImage ==NULL)
return NULL;

//swape the R and B values to get RGB sinse the bitmap color format is in BGR
for (imageIdx = 0; imageIdx < bitmapInfoHeader->biSizeImage; imageIdx+=3)
tempRGB = bitmapImage[imageIdx + 2];
bitmapImage[imageIdx] = bitmapImage[imageIdx + 2];
bitmapImage[imageIdx + 2] = tempRGB;

//close the file and return the bitmap image data
return bitmapImage;


Then after that you need to enable glTexture2D like so........
The code below load the BMP and bind it and textures it on the object.

-------start copying-------
copy this after the first code earlier and declare the init function at the begging of the file like so void init(void).
thats all and your done.

void init(void)
glClearColor(0.0f ,0.0f ,0.0f ,0.0f);

//loads BMP but change it to your file(this is mines).
bitmapData=LoadBitmapFile("C:/Documents and Setting/Owner/Desktop/DEV save/paint.bmp", &bitmapInfoHeader);

glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);

//load the texture image
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, bitmapInfoHeader.biWidth, bitmapInfoHeader.biHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, bitmapData);


Andrew rulz and u know it.........

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