www.pudn.com > Particles_OGL.zip > gl_texture.cpp

#include  
#include "gl_texture.h" 
#include "bitmap_class.h" 
#include "gl_obj.h" 
 
// Constructor -- Set everything to a default state 
CGLTexture::CGLTexture() 
{ 
	id = TEXTURE_NOT_LOADED; // Not loaded yet 
	angle = 0.0f; 
} 
 
// Loads the texture specified by "fileName".  Returns 
// true on success, false otherwise 
bool CGLTexture::load(const char *fileName, bool buildMipMaps) 
{ 
		// Error Check 
		if(!fileName) return false; 
		 
	// Can't load if already loaded 
	if(id != TEXTURE_NOT_LOADED) return false;  
	 
	CBitmap texture; 
	 
	// Try and load the texture 
	if(!texture.loadBMP(fileName)) 
		return false;								 
 
	// Generates a texture "name", for the number of textures 
	// passed in, in the texture name array passed in.  The CGLTexture 
	// class only encompasses a single texture, so we will always be  
	// generating one texture with one texture id 
	glGenTextures(1, (GLuint*)&id); 
 
	// Bind the texture to a particular format and location in a texture 
	// array. 
	glBindTexture(GL_TEXTURE_2D, id); 
	 
	// Determine the pixel layout of the image.  If it's a 24-bit .bmp 
	// then the pixels will be laid in BGR format, otherwise we'll 
	// assume it's a 32-bit .bmp and it's laid out in BGRA format 
	int pixelLayout = (texture.getChannels() == 3) ? GL_BGR_EXT : GL_BGRA_EXT; 
	 
	// Create the texture 
	// GL_TEXTURE_2D -- Type of texture, must be GL_TEXTURE_2D 
	// 0 -- Mip map level.  This is the raw texture so we use 0 
	// texture.getChannels() -- Number of channels in image.  Can also be special GL constants 
	// texture.getWidth() -- Width of image 
	// texture.getHeight() -- Height of image 
	// 0 -- Size of texture border.  Can either be 0 pixels or 1 pixel 
	// pixelLayout -- Layout of pixel data 
	// GL_UNSIGNED_BYTE -- Data type of pixel data 
	// texture.getLinePtr(0) -- Pointer to the texture's pixels 
	glTexImage2D(GL_TEXTURE_2D, 0, texture.getChannels(), texture.getWidth(), texture.getHeight(), 0, 
				 pixelLayout, GL_UNSIGNED_BYTE, texture.getLinePtr(0)); 
	 
	if(buildMipMaps) 
	{ 
		// Build Mipmaps 
		gluBuild2DMipmaps(GL_TEXTURE_2D, texture.getChannels(), texture.getWidth(), texture.getHeight(), 
						  pixelLayout, GL_UNSIGNED_BYTE, texture.getLinePtr(0)); 
						   
		// Specify texture quality		 
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); 
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // Can only be GL_NEAR  
																		 // or GL_LINEAR 
	} 
	else // Specify texture quality not considering mip-maps 
	{ 
		// Specify texture quality		 
		glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
		glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); 
	} 
	 
	return true; // Texture loaded successfully 
} 
 
// Selects this texture as the texture to be used for the drawing of any  
// geometry with a texture map -- Returns true for success, false otherwise 
bool CGLTexture::select() 
{ 
	// Can't select a texture that is not loaded 
	if(id == TEXTURE_NOT_LOADED) 
		return false; 
 
	// Load the texture matrix	 
	glMatrixMode(GL_TEXTURE); 
	glLoadIdentity(); 
	 
	// Rotate the UVs around the center of the texture 
	glTranslatef(0.5f, 0.5f, 0.0f); // Translate so center of texture is at the texture  
									 // coordinate system's origin 
	glRotatef(angle, 0.0f, 0.0f, 1.0f); // Rotate around the Z-axis  
	glTranslatef(-0.5f, -0.5f, 0.0f); // Translate back 
		 
	glBindTexture(GL_TEXTURE_2D, id); 
	glMatrixMode(GL_MODELVIEW); 
		return true; 
} 
 
// Free the texture resource 
void CGLTexture::freeMem() 
{ 
	if(id != TEXTURE_NOT_LOADED) 
	{ 
		glDeleteTextures(1, (GLuint*)&id); 
		id = TEXTURE_NOT_LOADED; 
	} 
} 
 
// Deconstructor 
CGLTexture::~CGLTexture() { freeMem(); }