TGA fiiles
Sorry, I just can't seem to get it. I have Beginning OpenGL Game programming the book, but I can't seem to grasp the TGA loading part. Can anyone post a simple bit of code that loads a tga, with no linked lists. I would appreciate it. And if you could explain each part and what it does. I'm a newbie so please don't slap me for asking this.
Adam L
If you need some TGA loading code I have a nice class that handles everything you need. So if you want it I'll give it to you.
Jake
Jake
Sure jake_Ghost, if you wouldn't mind also including descriptions of what certain things do in it that would be great!
Here is a good website for a description of the TGA file format:
TGA Format
I also have code that I can post that I used from this site.
TGA Format
I also have code that I can post that I used from this site.
Alight if you guys could help me debug that would be great. What happens is I get a bunch of verical bars. Multicolored bars. Hippi bars. Anyways, I'll post the code. Its long so bear with me please.
tga.h
Stuff to initialize once
stuff in loop
I'm not in a rush so take as long as you need to reply, if you reply at all. Sorry about all this.
tga.h
#include <windows.h> // Standard Windows header#include <stdio.h> // Standard Header For File I/O#include <gl\gl.h> // Standard Header For OpenGL#include <gl\glu.h>typedef struct { GLubyte* imageData; // Hold All The Color Values For The Image. GLuint bpp; // Hold The Number Of Bits Per Pixel. GLuint width; // The Width Of The Entire Image. GLuint height; // The Height Of The Entire Image. GLuint texID; // Texture ID For Use With glBindTexture. GLuint type; // Data Stored In * ImageData (GL_RGB Or GL_RGBA) } Texture; typedef struct { GLubyte Header[12]; // File Header To Determine File Type } TGAHeader;typedef struct { GLubyte header[6]; // Holds The First 6 Useful Bytes Of The File GLuint bytesPerPixel; // Number Of BYTES Per Pixel (3 Or 4) GLuint imageSize; // Amount Of Memory Needed To Hold The Image GLuint type; // The Type Of Image, GL_RGB Or GL_RGBA GLuint Height; // Height Of Image GLuint Width; // Width Of Image GLuint Bpp; // Number Of BITS Per Pixel (24 Or 32) } TGA;TGAHeader tgaheader; // Used To Store Our File HeaderTGA tga; // Used To Store File Information// Uncompressed TGA HeaderGLubyte uTGAcompare[12] = {0,0, 2,0,0,0,0,0,0,0,0,0};// Compressed TGA HeaderGLubyte cTGAcompare[12] = {0,0,10,0,0,0,0,0,0,0,0,0};// Load An Uncompressed Filebool LoadUncompressedTGA(Texture *, char *, FILE *);// Load A Compressed Filebool LoadCompressedTGA(Texture *, char *, FILE *);//load a tga filebool LoadTGA(Texture * texture, char * filename){ FILE * fTGA; // Declare File Pointer fTGA = fopen(filename, "rb"); // Open File For Reading if(fTGA == NULL) // If Here Was An Error { return false; // Return False } if(fread(&tgaheader, sizeof(TGAHeader), 1, fTGA) == 0) { return false; // Return False If It Fails } // If The File Header Matches The Uncompressed Header if(memcmp(uTGAcompare, &tgaheader, sizeof(tgaheader)) == 0) { // Load An Uncompressed TGA LoadUncompressedTGA(texture, filename, fTGA); } // If The File Header Matches The Compressed Header else if(memcmp(cTGAcompare, &tgaheader, sizeof(tgaheader)) == 0) { // Load A Compressed TGA LoadCompressedTGA(texture, filename, fTGA); } else // If It Doesn't Match Either One { fclose(fTGA); return false; // Return False } } // Load An Uncompressed TGA!bool LoadUncompressedTGA(Texture * texture, char * filename, FILE * fTGA){ // Attempt To Read Next 6 Bytes if(fread(tga.header, sizeof(tga.header), 1, fTGA) == 0) { return false; // Return False } texture->width = tga.header[1] * 256 + tga.header[0]; // Calculate Height texture->height = tga.header[3] * 256 + tga.header[2]; // Calculate The Width texture->bpp = tga.header[4]; // Calculate Bits Per Pixel tga.Width = texture->width; // Copy Width Into Local Structure tga.Height = texture->height; // Copy Height Into Local Structure tga.Bpp = texture->bpp; // Copy Bpp Into Local Structure // Make Sure All Information Is Valid if((texture->width <= 0) || (texture->height <= 0) || ((texture->bpp != 24) && (texture->bpp !=32))) { return false; // Return False } if(texture->bpp == 24) // Is It A 24bpp Image? texture->type = GL_RGB; // If So, Set Type To GL_RGB else // If It's Not 24, It Must Be 32 texture->type = GL_RGBA; // So Set The Type To GL_RGBA tga.bytesPerPixel = (tga.Bpp / 8); // Calculate The BYTES Per Pixel // Calculate Memory Needed To Store Image tga.imageSize = (tga.bytesPerPixel * tga.Width * tga.Height); // Allocate Memory texture->imageData = (GLubyte *)malloc(tga.imageSize); if(texture->imageData == NULL) // Make Sure It Was Allocated Ok { return false; // If Not, Return False } // Attempt To Read All The Image Data if(fread(texture->imageData, 1, tga.imageSize, fTGA) != tga.imageSize) { return false; // If We Cant, Return False } // Start The Loop for(GLuint cswap = 0; cswap < (int)tga.imageSize; cswap += tga.bytesPerPixel) { // 1st Byte XOR 3rd Byte XOR 1st Byte XOR 3rd Byte texture->imageData[cswap] ^= texture->imageData[cswap+2] ^= texture->imageData[cswap] ^= texture->imageData[cswap+2]; } fclose(fTGA); // Close The File return true; // Return Success}bool LoadCompressedTGA(Texture * texture, char * filename, FILE * fTGA) { if(fread(tga.header, sizeof(tga.header), 1, fTGA) == 0) // Attempt to read header { MessageBox(NULL, "Could not read info header", "ERROR", MB_OK); // Display Error if(fTGA != NULL) // If file is open { fclose(fTGA); // Close it } return false; // Return failed } texture->width = tga.header[1] * 256 + tga.header[0]; // Determine The TGA Width (highbyte*256+lowbyte) texture->height = tga.header[3] * 256 + tga.header[2]; // Determine The TGA Height (highbyte*256+lowbyte) texture->bpp = tga.header[4]; // Determine Bits Per Pixel tga.Width = texture->width; // Copy width to local structure tga.Height = texture->height; // Copy width to local structure tga.Bpp = texture->bpp; // Copy width to local structure if((texture->width <= 0) || (texture->height <= 0) || ((texture->bpp != 24) && (texture->bpp !=32))) //Make sure all texture info is ok { MessageBox(NULL, "Invalid texture information", "ERROR", MB_OK); // If it isnt...Display error if(fTGA != NULL) // Check if file is open { fclose(fTGA); // Ifit is, close it } return false; // Return failed } tga.bytesPerPixel = (tga.Bpp / 8); // Compute BYTES per pixel tga.imageSize = (tga.bytesPerPixel * tga.Width * tga.Height); // Compute amout of memory needed to store image texture->imageData = (GLubyte *)malloc(tga.imageSize); // Allocate that much memory if(texture->imageData == NULL) // If it wasnt allocated correctly.. { MessageBox(NULL, "Could not allocate memory for image", "ERROR", MB_OK); // Display Error fclose(fTGA); // Close file return false; // Return failed } GLuint pixelcount = tga.Height * tga.Width; // Nuber of pixels in the image GLuint currentpixel = 0; // Current pixel being read GLuint currentbyte = 0; // Current byte GLubyte * colorbuffer = (GLubyte *)malloc(tga.bytesPerPixel); // Storage for 1 pixel do { GLubyte chunkheader = 0; // Storage for "chunk" header if(fread(&chunkheader, sizeof(GLubyte), 1, fTGA) == 0) // Read in the 1 byte header { MessageBox(NULL, "Could not read RLE header", "ERROR", MB_OK); // Display Error if(fTGA != NULL) // If file is open { fclose(fTGA); // Close file } if(texture->imageData != NULL) // If there is stored image data { free(texture->imageData); // Delete image data } return false; // Return failed } if(chunkheader < 128) // If the ehader is < 128, it means the that is the number of RAW color packets minus 1 { // that follow the header chunkheader++; // add 1 to get number of following color values for(short counter = 0; counter < chunkheader; counter++) // Read RAW color values { if(fread(colorbuffer, 1, tga.bytesPerPixel, fTGA) != tga.bytesPerPixel) // Try to read 1 pixel { MessageBox(NULL, "Could not read image data", "ERROR", MB_OK); // IF we cant, display an error if(fTGA != NULL) // See if file is open { fclose(fTGA); // If so, close file } if(colorbuffer != NULL) // See if colorbuffer has data in it { free(colorbuffer); // If so, delete it } if(texture->imageData != NULL) // See if there is stored Image data { free(texture->imageData); // If so, delete it too } return false; // Return failed } // write to memory texture->imageData[currentbyte ] = colorbuffer[2]; // Flip R and B vcolor values around in the process texture->imageData[currentbyte + 1 ] = colorbuffer[1]; texture->imageData[currentbyte + 2 ] = colorbuffer[0]; if(tga.bytesPerPixel == 4) // if its a 32 bpp image { texture->imageData[currentbyte + 3] = colorbuffer[3]; // copy the 4th byte } currentbyte += tga.bytesPerPixel; // Increase thecurrent byte by the number of bytes per pixel currentpixel++; // Increase current pixel by 1 if(currentpixel > pixelcount) // Make sure we havent read too many pixels { MessageBox(NULL, "Too many pixels read", "ERROR", NULL); // if there is too many... Display an error! if(fTGA != NULL) // If there is a file open { fclose(fTGA); // Close file } if(colorbuffer != NULL) // If there is data in colorbuffer { free(colorbuffer); // Delete it } if(texture->imageData != NULL) // If there is Image data { free(texture->imageData); // delete it } return false; // Return failed } } } else // chunkheader > 128 RLE data, next color reapeated chunkheader - 127 times { chunkheader -= 127; // Subteact 127 to get rid of the ID bit if(fread(colorbuffer, 1, tga.bytesPerPixel, fTGA) != tga.bytesPerPixel) // Attempt to read following color values { MessageBox(NULL, "Could not read from file", "ERROR", MB_OK); // If attempt fails.. Display error (again) if(fTGA != NULL) // If thereis a file open { fclose(fTGA); // Close it } if(colorbuffer != NULL) // If there is data in the colorbuffer { free(colorbuffer); // delete it } if(texture->imageData != NULL) // If thereis image data { free(texture->imageData); // delete it } return false; // return failed } for(short counter = 0; counter < chunkheader; counter++) // copy the color into the image data as many times as dictated { // by the header texture->imageData[currentbyte ] = colorbuffer[2]; // switch R and B bytes areound while copying texture->imageData[currentbyte + 1 ] = colorbuffer[1]; texture->imageData[currentbyte + 2 ] = colorbuffer[0]; if(tga.bytesPerPixel == 4) // If TGA images is 32 bpp { texture->imageData[currentbyte + 3] = colorbuffer[3]; // Copy 4th byte } currentbyte += tga.bytesPerPixel; // Increase current byte by the number of bytes per pixel currentpixel++; // Increase pixel count by 1 if(currentpixel > pixelcount) // Make sure we havent written too many pixels { MessageBox(NULL, "Too many pixels read", "ERROR", NULL); // if there is too many... Display an error! if(fTGA != NULL) // If there is a file open { fclose(fTGA); // Close file } if(colorbuffer != NULL) // If there is data in colorbuffer { free(colorbuffer); // Delete it } if(texture->imageData != NULL) // If there is Image data { free(texture->imageData); // delete it } return false; // Return failed } } } } while(currentpixel < pixelcount); // Loop while there are still pixels left fclose(fTGA); // Close the file return true; // return success}
Stuff to initialize once
Texture texture; glEnable(GL_TEXTURE_2D); // Enable Texture Mapping ( NEW ) glShadeModel(GL_SMOOTH); // Enable Smooth Shading glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background glClearDepth(1.0f); // Depth Buffer Setup glEnable(GL_DEPTH_TEST); // Enables Depth Testing glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations LoadTGA(&texture, "lightsaber.tga"); glGenTextures(1, &texture.texID); // Create The Texture // Typical Texture Generation Using Data From The Bitmap glBindTexture(GL_TEXTURE_2D, texture.texID); glTexImage2D(GL_TEXTURE_2D, 0, 3, texture.width, texture.height, 0, GL_RGB, GL_UNSIGNED_BYTE, texture.imageData); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
stuff in loop
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer glLoadIdentity(); glBindTexture(GL_TEXTURE_2D, texture.texID); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad glEnd(); SwapBuffers(hDC);
I'm not in a rush so take as long as you need to reply, if you reply at all. Sorry about all this.
Quote:Original post by AdamGL
What happens is I get a bunch of verical bars. Multicolored bars. Hippi bars.
Does the problem happen with all .tga textures you try, or just with some of them? More specifically... do you get the same effect with both uncompressed and compressed textures, or just with one of these types..?
thanks man, that was a big waste of space up there. It shows up, the same type of tga uncompressed and 32 bit. How do I make a proper tga file. What aree my limitations?
This topic is closed to new replies.
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