Which is the best way (lowest memory, fastest speed) to texture a cube? after a while i have find this solution:
data struct:
GLfloat Cube::vertices[] =
{-0.5f, 0.0f, 0.5f, 0.5f, 0.0f, 0.5f, 0.5f, 1.0f, 0.5f, -0.5f, 1.0f, 0.5f,
-0.5f, 1.0f, -0.5f, 0.5f, 1.0f, -0.5f, 0.5f, 0.0f, -0.5f, -0.5f, 0.0f, -0.5f,
0.5f, 0.0f, 0.5f, 0.5f, 0.0f, -0.5f, 0.5f, 1.0f, -0.5f, 0.5f, 1.0f, 0.5f,
-0.5f, 0.0f, -0.5f, -0.5f, 0.0f, 0.5f, -0.5f, 1.0f, 0.5f, -0.5f, 1.0f, -0.5f
};
GLfloat Cube::texcoords[] = { 0.0,0.0, 1.0,0.0, 1.0,1.0, 0.0,1.0,
0.0,0.0, 1.0,0.0, 1.0,1.0, 0.0,1.0,
0.0,0.0, 1.0,0.0, 1.0,1.0, 0.0,1.0,
0.0,0.0, 1.0,0.0, 1.0,1.0, 0.0,1.0
};
GLubyte Cube::cubeIndices[24] = {0,1,2,3, 4,5,6,7, 3,2,5,4, 7,6,1,0,
8,9,10,11, 12,13,14,15};
draw function:
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glColor3f(1.0f, 1.0f, 1.0f);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glTexCoordPointer(2, GL_FLOAT, 0, texcoords);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glDrawElements(GL_QUADS, 24, GL_UNSIGNED_BYTE, cubeIndices);
glDisableClientState(GL_VERTEX_ARRAY);
//glDisableClientState(GL_COLOR_ARRAY);
glDisable(GL_TEXTURE_2D);
As you can see the result is correct:
but to rech this result i have to redefine some vertex (there are 16 3D points in the vertices
array) otherwise the texture fail to map in the DrawElement function.
Someone knows a better way to texture a cube in a vertex array?
I ran into the same issue a while back working with opengl es. My research indicated that there was no other way to do it because each vertex could only have one texture coordinate associated with it.