[OpenGL] graphics Journey: texture Paster Trilogy

Next, we will introduce texture pasters in OpenGL in the following three steps:

0. Declare the data for storing textures:

# Define maxtexture 1 gluint texture [maxtexture]; // defines a texture array for storing the subsequent Image Texture Information

1. Introduce BMP bitmap:

Aux_rgbimagerec * LoadImage (char * filename) // load bitmap data {file * file = NULL; If (! Filename) {return NULL;} file = fopen (filename, "R"); If (File) {fclose (File); Return auxdibimageload (filename);} return NULL ;}

2. Convert the loaded bitmap into a texture:

Bool loadtexturegl (void) // convert the loaded bitmap to a texture {bool state = false; aux_rgbimagerec * textureimage [maxtexture]; // create a texture storage space memset (textureimage, 0, sizeof (void *) * maxtexture); // clear the image information in the texture bucket as null // load the image and check whether an error occurs, if the image does not exist, if (textureimage [0] = LoadImage ("Data/sky.bmp") {state = true; glgentextures (maxtexture, & texture [0]) is returned. // convert the loaded image into a texture and save it to the texture array. // use the image data to generate a texture for (INT I = 0; I <maxtexture; ++ I) {glbindtexture (gl_texture_2d, texture [I]); // use the typical texture generated from the bitmap data // generate the texture glubuild2dmipmaps (gl_texture_2d, 3, textureimage [I]-> sizex, textureimage [I]-> sizey, gl_rgb, gl_unsigned_byte, textureimage [I]-> data); gltexparameteri (gl_texture_2d, gl_texture_min_filter, gl_linear ); // when the texture is enlarged to the original texture (gl_texture_mag_filter) or smaller than the original texture (gl_texture_min_filter), gltexparameteri (gl_texture_2d, cosine, gl_linear) is used in linear filtering );}} for (INT I = 0; I <maxtexture; ++ I) // release the memory used to store bitmap information {If (textureimage [I]) {If (textureimage [I]-> data) {free (textureimage [I]-> data);} Free (textureimage [I]);} return state ;}

3. Apply texture maps to the scene:

Void gamescene: drawsky () {gl_texture_2d); // enable the texture ing glable (gl_depth_test); // enable the deep test gldisable (gl_blend ); // disable the mixed loadtexturegl (); glbindtexture (gl_texture_2d, texture [0]); // bind the texture to glbegin (gl_quads) on the object drawn below ); // The coordinate on the left is the source image. The source image must be an integer multiple of 2. The minimum value is 64*64, and the value is 128*128. The maximum value is 256*256. // The coordinate gltexcoord2f (0.0f, 0.0f), glvertex3f (0.0f, 1.0f, 1.0f), gltexcoord2f (1.0f, 0.0f), glvertex3f (1.0f, 1.0f, 1.0f, 1.0f); random (1.0f, 1.0f); glvertex3f (1.0f, 1.0f, 0.0f); gltexcoord2f (0.0f, 1.0f); glvertex3f (0.0f, 1.0f, 0.0f); glend (); gldisable (gl_texture_2d); // enable the texture ing gldisable (gl_depth_test); // enable the deep test}

Texture maps are completed in the preceding three steps.