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POProblems Displaying Targa/TGA
 

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  1. POProblems Displaying Targa/TGA
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    <p>Very very slight problem with my Targa Reader. One pixel is off and 2 extra pixels are black :S</p> <p>The 24-bit targa file I'm loading looks like: <img src="https://i.stack.imgur.com/2S9hh.png" alt="enter image description here"></p> <p>Notice the White pixel in the very top left corner. The very first pixel at the top left is white.</p> <p>But when I save the file pixels back as a 24-bit bitmap, it looks like: <img src="https://i.stack.imgur.com/6IGQx.png" alt="enter image description here"></p> <p>Notice that the white pixel is somehow in the top right as well as 2 black pixels above it.</p> <p>I cannot for the life of me figure out why everything else is correct except for that.. It's bothering me because I'm so close to being able to load TGA's.</p> <p>Any idea what is wrong with my code below? I'm writing the TGA reader for 16, 24 and 32 bit TGA files created with Photoshop.</p> <pre><code>typedef union RGB //Struct which will hold all pixels. { uint32_t Color; struct { unsigned char B, G, R, A; } RGBA; } *PRGB; class Tga //My Targa class that will load the TGA file. { private: std::vector&lt;RGB&gt; Pixels; uint32_t width, height, size, BitsPerPixel; public: Tga(const char* FilePath); }; Tga::Tga(const char* FilePath) { //Open the file for reading.. std::fstream hFile(FilePath, std::ios::in | std::ios::binary); if (!hFile.is_open()){throw std::invalid_argument("File Not Found.");} //The header is 12 bytes. By reading it, I can tell if the TGA is compressed or not. byte Header[12] = {0}; byte DeCompressed[12] = {0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}; byte IsCompressed[12] = {0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}; hFile.read(reinterpret_cast&lt;char*&gt;(&amp;Header), sizeof(Header)); //Read the header. if (memcmp(DeCompressed, &amp;Header, sizeof(Header)) == 0) //If it is not compressed. { hFile.read(reinterpret_cast&lt;char*&gt;(&amp;Header), sizeof(Header)); BitsPerPixel = Header[4]; //Displays correctly. width = Header[1] * 256 + Header[0]; //Displays correctly. height = Header[3] * 256 + Header[2]; //Displays correctly. size = ((width * BitsPerPixel + 31) / 32) * 4 * height; //Same algorithm for bitmaps. width * height * 3 OR width * height * 4. Taken from MSDN. if ((BitsPerPixel != 24) &amp;&amp; (BitsPerPixel != 32) &amp;&amp; ((width &lt; 1) || (height &lt; 1))) { hFile.close(); throw std::logic_error("Error: Invalid TGA File. Width And Height cannot be less than 0. BitsPerPixel must be 24 or 32 bits."); } std::vector&lt;unsigned char&gt; ImageData(size); //An array for holding the image data. hFile.read(reinterpret_cast&lt;char*&gt;(ImageData.data()), size); unsigned char* BuffPos = ImageData.data(); Pixels.resize(width * height); //A vector holding my structs that will hold the pxiels. //The following is supposed to flip the Image and copy it into my struct vector. for (int I = 0; I &lt; height; I++) { for (int J = 0; J &lt; width; J++) { Pixels[(height - 1 - I) * width + J].RGBA.B = *(BuffPos++); Pixels[(height - 1 - I) * width + J].RGBA.G = *(BuffPos++); Pixels[(height - 1 - I) * width + J].RGBA.R = *(BuffPos++); Pixels[(height - 1 - I) * width + J].RGBA.A = (BitsPerPixel &gt; 24 ? *(BuffPos++) : 0xFF); } if(BitsPerPixel == 24) //Has padding? BuffPos += (4 - ((width * 3) % 4)) % 4; } } else if (memcmp(IsCompressed, &amp;Header, sizeof(Header)) == 0) //The TGA is compressed.. { hFile.read(reinterpret_cast&lt;char*&gt;(&amp;Header), sizeof(Header)); BitsPerPixel = Header[4]; height = Header[1] * 256 + Header[0]; width = Header[3] * 256 + Header[2]; size = ((width * BitsPerPixel + 31) / 32) * 4 * height; if ((BitsPerPixel != 24) &amp;&amp; (BitsPerPixel != 32) &amp;&amp; ((width &lt; 1) || (height &lt; 1))) { hFile.close(); throw std::logic_error("Error: Invalid TGA File. Width And Height cannot be less than 0. BitsPerPixel must be 24 or 32 bits."); } RGB Pixel = {0}; char* BuffPos = reinterpret_cast&lt;char*&gt;(&amp;Pixel); int CurrentByte = 0, CurrentPixel = 0; int BytesPerPixel = (BitsPerPixel / 8); Pixels.resize(width * height * sizeof(RGB)); do { byte ChunkHeader = 0; hFile.read(reinterpret_cast&lt;char*&gt;(&amp;ChunkHeader), sizeof(byte)); if (ChunkHeader &lt; 128) { ++ChunkHeader; for (int I = 0; I &lt; ChunkHeader; ++I) { hFile.read(BuffPos, BytesPerPixel); Pixels[CurrentByte].RGBA.B = Pixel.RGBA.B; Pixels[CurrentByte].RGBA.G = Pixel.RGBA.G; Pixels[CurrentByte].RGBA.R = Pixel.RGBA.R; Pixels[CurrentByte].RGBA.A = (BitsPerPixel &gt; 24) ? Pixel.RGBA.A : 0xFF; CurrentByte += BytesPerPixel; ++CurrentPixel; } } else { ChunkHeader -= 127; hFile.read(BuffPos, BytesPerPixel); for (int I = 0; I &lt; ChunkHeader; ++I) { Pixels[CurrentByte].RGBA.B = Pixel.RGBA.B; Pixels[CurrentByte].RGBA.G = Pixel.RGBA.G; Pixels[CurrentByte].RGBA.R = Pixel.RGBA.R; Pixels[CurrentByte].RGBA.A = (BitsPerPixel &gt; 24) ? Pixel.RGBA.A : 0xFF; CurrentByte += BytesPerPixel; ++CurrentPixel; } } } while(CurrentPixel &lt; (width * height)); } hFile.close(); //I can guarantee nothing is wrong with the bitmap creator. Bitmap BMP(width, height, 24); //Take the pixels structure and create a 24 bit bitmap. This works 100% of the time for PNG and Bitmap using the same structure. BMP.Set(Pixels); BMP.Save("C:/Foo.bmp"); } int main() { Tga F("C:/Foo.tga"); } </code></pre>
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