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POc++ tga parsing incorrect_color/distortion with some resolutions
 

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  1. POc++ tga parsing incorrect_color/distortion with some resolutions
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    <p>i'd like to get some help on my issue with .tga file format parsing. i have the code, which i use for a long time: </p> <pre><code> int fileLength = Input.tellg(); vector&lt;char&gt; tempData; tempData.resize(fileLength); Input.seekg(0); Input.read(&amp;tempData[0], fileLength); Input.close(); // Load information about the tga, aka the header. // Seek to the width. w = byteToUnsignedShort(tempData[12], tempData[13]); // Seek to the height. h = byteToUnsignedShort(tempData[14], tempData[15]); // Seek to the depth. depth = unsigned(tempData[16]); // Mode = components per pixel. md = depth / 8; // Total bytes = h * w * md. t = h * w * md; //Delete allocated data, if need to clear(); //Allocate new storage data.resize(t); // Copy image data. for(unsigned i = 0, s = 18; s &lt; t + 18; s++, i++) data[i] = unsigned char(tempData[s]); // Mode 3 = RGB, Mode 4 = RGBA // TGA stores RGB(A) as BGR(A) so // we need to swap red and blue. if(md &gt; 2) { char aux; for(unsigned i = 0; i &lt; t; i+= md) { aux = data[i]; data[i] = data[i + 2]; data[i + 2] = aux; } } </code></pre> <p>but it keeps failing occasionally for some image resolutions(mostly odd numbers and non-POT resolutions). it results in distorted image(with diagonal patterns) or wrong colors. last time i've encountered it - it was 9x9 24bpp image showing weird colors.</p> <p>i'm on windows(so it means little-endian), rendering with opengl(i'm taking in account alpha channel existence, when passing image data with glTexImage2D). i'm saving my images with photoshop, not setting RLE flag. this code always reads correct image resolution and color depth.</p> <p>example of image causing trouble: <a href="http://pastie.org/private/p81wbh5sb6coldspln6mw" rel="nofollow">http://pastie.org/private/p81wbh5sb6coldspln6mw</a></p> <p>after loading problematic image, this code:</p> <pre><code>for(unsigned f = 0; f &lt; imageData.w * imageData.h * imageData.depth; f += imageData.depth) { if(f % (imageData.w * imageData.depth) == 0) writeLog &lt;&lt; endl; writeLog &lt;&lt; "[" &lt;&lt; unsigned(imageData.data[f]) &lt;&lt; "," &lt;&lt; unsigned(imageData.data[f + 1]) &lt;&lt; "," &lt;&lt; unsigned(imageData.data[f + 2]) &lt;&lt; "]" &lt;&lt; flush; } </code></pre> <p>outputs this:</p> <pre><code>[37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40] [37,40,40][173,166,164][93,90,88][93,90,88][93,90,88][93,90,88][93,90,88][88,85,83][37,40,40] [37,40,40][228,221,219][221,212,209][221,212,209][221,212,209][221,212,209][221,212,209][140,134,132][37,40,40] [37,40,40][228,221,219][221,212,209][221,212,209][221,212,209][221,212,209][221,212,209][140,134,132][37,40,40] [37,40,40][228,221,219][221,212,209][221,212,209][221,212,209][221,212,209][221,212,209][140,134,132][37,40,40] [37,40,40][228,221,219][221,212,209][221,212,209][221,212,209][221,212,209][221,212,209][140,134,132][37,40,40] [37,40,40][228,221,219][221,212,209][221,212,209][221,212,209][221,212,209][221,212,209][140,134,132][37,40,40] [37,40,40][237,232,230][235,229,228][235,229,228][235,229,228][235,229,228][235,229,228][223,214,212][37,40,40] [37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40][37,40,40] </code></pre> <p>so i guess it does read correct data. that brings us to opengl;</p> <pre><code>glGenTextures(1, &amp;textureObject); glBindTexture(GL_TEXTURE_2D, textureObject); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); GLenum in_comp_mode, comp_mode; if(linear) //false for that image glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); else glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); //i don't use 1 or 2 - channel textures, so it's always 24 or 32bpp if(imageData.depth == 24) { in_tex_mode = GL_RGB8; tex_mode = GL_RGB; } else { in_tex_mode = GL_RGBA8; tex_mode = GL_RGBA; } glTexImage2D(GL_TEXTURE_2D, 0, in_tex_mode, imageData.w, imageData.h, 0, tex_mode, GL_UNSIGNED_BYTE, &amp;imageData.data[0]); glBindTexture(GL_TEXTURE_2D, NULL); </code></pre> <p>texture compression code is omitted, 'cause it's not active for that texture.</p>
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