OpenGL loads BMP files

The following code is from nehe, based on the framework of Lesson 1:

Http://download.csdn.net/source/1907052

 

 

1. define a global variable to store the BMP file:

Gluint texture [1]; // stores a texture

 

2. Define two functions to load the BMP file:

/* <Br/> * loadbmp <br/> * load bitmap image <br/> */<br/> aux_rgbimagerec * loadbmp (char * filename) <br/>{< br/> file * file = NULL; <br/> If (! Filename) <br/>{< br/> return NULL; <br/>}</P> <p> // try to open the file <br/> file = fopen (filename, "R"); <br/> If (file) <br/>{< br/> fclose (File); <br/> return auxdibimageload (filename ); // load the bitmap and return the pointer <br/>}< br/> return NULL; <br/>}</P> <p>/* <br/> * loadgltextures <br/> * load a bitmap (call the above Code) convert to texture <br/> */<br/> int loadgltextures () <br/>{< br/> int status = false; // Status Indicator <br/> aux_rgbimagerec * textureimage [1]; // create a texture bucket <br/> memset (textureimage, 0, sizeof (void *) * 1); </P> <p> // load the bitmap to check for any errors, if the bitmap is not found, exit <br/> If (textureimage [0] = loadbmp ("xiaoshe.bmp") <br/>{< br/> Status = true; </P> <p> // create texture <br/> glgentextures (1, & texture [0]); <br/> // use a typical texture generated from the bitmap data <br/> glbindtexture (gl_texture_2d, texture [0]); <br/> // generate texture <br/> glteximage2d (gl_texture_2d, 0, 3, textureimage [0]-> sizex, textureimage [0]-> sizey, 0, gl_rgb, response, textureimage [0]-> data); <br/> gltexparameteri (gl_texture_2d, cosine, gl_linear); // linear filtering <br/> gltexparameteri (gl_texture_2d, cosine, gl_linear); <br/>}</P> <p> // release bitmap data <br/> If (textureimage [0]) // whether the texture exists <br/>{< br/> If (textureimage [0]-> data) // whether the texture image exists <br/>{< br/> free (textureimage [0]-> data ); // release the memory occupied by the texture image <br/>}< br/> free (textureimage [0]); // release the image structure <br/>}</P> <p> return status; <br/>}

3. Load BMP in initgl (glvoid) and enable texture ing:

// Call the texture loading subroutine <br/> If (! Loadgltextures () <br/>{< br/> return 0; <br/>}< br/> glable (gl_texture_2d); // enable texture ing

4. Draw a quadrilateral display BMP file in drawglscence (glvoid:

 Glbindtexture (gl_texture_2d, texture [0]); // select the texture </P> <p> glbegin (gl_quads); <br/> gltexcoord2f (0.0f, 1.0f ); // top left <br/> glvertex3f (-1.0f, 1.0f, 0.0f); // top left </P> <p> gltexcoord2f (1.0f, 1.0f ); // upper right <br/> glvertex3f (1.0f, 1.0f, 0.0f); // upper right </P> <p> gltexcoord2f (1.0f, 0.0f ); // bottom right <br/> glvertex3f (1.0f,-1.0f, 0.0f); // bottom right </P> <p> gltexcoord2f (0.0f, 0.0f ); // bottom left <br/> glvertex3f (-1.0f,-1.0f, 0.0f); // bottom left <br/> glend ();