grafikaKBT/texture.cpp

#include "texture.hpp"

GLuint loadBMP_custom(const char * imagepath){

	return 0;

	timestampedCout("texture.cpp: Reading image " << imagepath << "...");

	// Data read from the header of the BMP file
	unsigned char header[54];
	unsigned int dataPos;
	unsigned int imageSize;
	unsigned int width, height;
	// Actual RGB data
	unsigned char * data;

	// Open the file
	FILE * file = fopen(imagepath, "rb");
	if (!file) {
		timestampedCout("texture.cpp: " << imagepath << " could not be opened. Are you in the right directory?");
		return 0;
	}

	// Read the header, i.e. the 54 first bytes

	// If less than 54 bytes are read, problem
	if (fread(header, 1, 54, file) != 54) {
		timestampedCout("texture.cpp: Not a correct BMP file.");
		fclose(file);
		return 0;
	}
	// A BMP files always begins with "BM"
	if (header[0] != 'B' || header[1] != 'M') {
		timestampedCout("texture.cpp: Not a correct BMP file.");
		fclose(file);
		return 0;
	}
	// Make sure this is a 24bpp file
	if (*(int*)&(header[0x1E]) !=  0) { timestampedCout("texture.cpp: Not a correct BMP file."); fclose(file); return 0;}
	if (*(int*)&(header[0x1C]) != 24) { timestampedCout("texture.cpp: Not a correct BMP file."); fclose(file); return 0;}

	// Read the information about the image
	dataPos   = *(int*)&(header[0x0A]);
	imageSize = *(int*)&(header[0x22]);
	width     = *(int*)&(header[0x12]);
	height    = *(int*)&(header[0x16]);

	// Some BMP files are misformatted, guess missing information
	if (imageSize == 0) imageSize = width * height * 3; // 3 : one byte for each Red, Green and Blue component
	if (dataPos   == 0) dataPos = 54;                   // The BMP header is done that way

	// Create a buffer
	data = new unsigned char [imageSize];

	// Read the actual data from the file into the buffer
	fread(data, 1, imageSize, file);

	// Everything is in memory now, the file can be closed.
	fclose(file);

	// Create one OpenGL texture
	GLuint textureID;
	glGenTextures(1, &textureID);
	
	// "Bind" the newly created texture : all future texture functions will modify this texture
	glBindTexture(GL_TEXTURE_2D, textureID);

	// Give the image to OpenGL
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);

	// OpenGL has now copied the data. Free our own version
	delete [] data;

	// Poor filtering, or ...
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

	// ... nice trilinear filtering ...
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	// ... which requires mipmaps. Generate them automatically.
	glGenerateMipmap(GL_TEXTURE_2D);

	// Return the ID of the texture we just created
	return textureID;
}

#define FOURCC_DXT1 0x31545844 // Equivalent to "DXT1" in ASCII
#define FOURCC_DXT3 0x33545844 // Equivalent to "DXT3" in ASCII
#define FOURCC_DXT5 0x35545844 // Equivalent to "DXT5" in ASCII

GLuint loadDDS(const char * imagepath){

	return 0;

	unsigned char header[124];

	FILE *fp;
 
	// timestampedCout("texture.cpp: Hello!");

	/* try to open the file */
	fp = fopen(imagepath, "rb");
	if (fp == NULL){
		timestampedCout("texture.cpp: " << imagepath << " could not be opened. Are you in the right directory?");
		return 0;
	}

	/* verify the type of file */
	char filecode[4];
	fread(filecode, 1, 4, fp);
	if (strncmp(filecode, "DDS ", 4) != 0) {
		fclose(fp);
		return 0;
	}
	
	/* get the surface desc */
	fread(&header, 124, 1, fp);

	unsigned int height      = *(unsigned int*)&(header[8 ]);
	unsigned int width	     = *(unsigned int*)&(header[12]);
	unsigned int linearSize	 = *(unsigned int*)&(header[16]);
	unsigned int mipMapCount = *(unsigned int*)&(header[24]);
	unsigned int fourCC      = *(unsigned int*)&(header[80]);

 
	unsigned char * buffer;
	unsigned int bufsize;
	/* how big is it going to be including all mipmaps? */
	bufsize = mipMapCount > 1 ? linearSize * 2 : linearSize;
	buffer = (unsigned char*)malloc(bufsize * sizeof(unsigned char));
	fread(buffer, 1, bufsize, fp);
	/* close the file pointer */
	fclose(fp);

	unsigned int components = (fourCC == FOURCC_DXT1) ? 3 : 4;
	unsigned int format;
	switch(fourCC) {

		case FOURCC_DXT1:
			format = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
			break;
		case FOURCC_DXT3:
			format = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
			break;
		case FOURCC_DXT5:
			format = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
			break;
		default:
			free(buffer);
			return 0;

	}

	// Create one OpenGL texture
	GLuint textureID;
	glGenTextures(1, &textureID);

	// "Bind" the newly created texture : all future texture functions will modify this texture
	glBindTexture(GL_TEXTURE_2D, textureID);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
	
	unsigned int blockSize = (format == GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) ? 8 : 16;
	unsigned int offset = 0;

	/* load the mipmaps */
	for (unsigned int level = 0; level < mipMapCount && (width || height); ++level) {

		unsigned int size = ((width + 3) / 4) * ((height + 3) / 4) * blockSize;
		glCompressedTexImage2D(GL_TEXTURE_2D, level, format, width, height,
			0, size, buffer + offset);
	 
		offset += size;
		width  /= 2;
		height /= 2;

		// Deal with Non-Power-Of-Two textures. This code is not included in the webpage to reduce clutter.
		if (width  < 1)  width = 1;
		if (height < 1) height = 1;

	}

	free(buffer);
	return textureID;

}