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POBuggy UV coordinates of sphere in OpenGL?
 

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  1. POBuggy UV coordinates of sphere in OpenGL?
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    <p>I am having buggy texture map on my sphere. The issue is well known but solution is rare.</p> <p>This is my code for generating UVs for a sphere.</p> <p>T = trinagles, Nv = vertex normals.</p> <pre><code>for (int i=0; i&lt;nbF; i++) { float tx1 = atan2(Nv[T[i].v1].x, Nv[T[i].v1].z) / (2.0f*M_PI) + 0.5f; float ty1 = asinf(Nv[T[i].v1].y) / M_PI + 0.5f; float tx2 = atan2(Nv[T[i].v2].x, Nv[T[i].v2].z) / (2.0f*M_PI) + 0.5f; float ty2 = asinf(Nv[T[i].v2].y) / M_PI + 0.5f; float tx3 = atan2(Nv[T[i].v3].x, Nv[T[i].v3].z) / (2.0f*M_PI) + 0.5f; float ty3 = asinf(Nv[T[i].v3].y) / M_PI + 0.5f; float n = 0.75f; if(tx2 &lt; n &amp;&amp; tx1 &gt; n) tx2 += 1.0; else if(tx2 &gt; n &amp;&amp; tx1 &lt; n) tx2 -= 1.0; if(tx3 &lt; n &amp;&amp; tx2 &gt; n) tx3 += 1.0; else if(tx3 &gt; n &amp;&amp; tx2 &lt; n) tx3 -= 1.0; out_UV[T[i].v1].u = tx1; out_UV[T[i].v1].v = ty1; out_UV[T[i].v2].u = tx2; out_UV[T[i].v2].v = ty2; out_UV[T[i].v3].u = tx3; out_UV[T[i].v3].v = ty3; } </code></pre> <p>Output: <a href="http://i.stack.imgur.com/luhgZ.jpg" rel="nofollow">http://i.stack.imgur.com/luhgZ.jpg</a> ![enter image description here][1]</p> <p>As you can see in the figure, my code is generating long strip at one side of the sphere. The solution is here .. <a href="http://sol.gfxile.net/sphere/index.html" rel="nofollow">http://sol.gfxile.net/sphere/index.html</a> but couldn't figure it out.. How can I solve this issue ? any suggestion?</p> <pre><code># Update 1:# </code></pre> <p>This code also doesn't work for me.. I don't know what wrong in it. still the same ugly seam I am getting. ???</p> <pre><code>for (int i=0; i&lt;nbV; i++) { out_UV[i].u = (float) atan2(Nv[i].x, Nv[i].z) / (2.0f*M_PI) + 0.5f; out_UV[i].v = (float) (asin(Nv[i].y) / M_PI) + 0.5f; } float nx = 0.9f; float nv = 0.8f; for (int i=0; i&lt;nbV-2; i++) { if (out_UV[i].u - out_UV[i+1].u &gt; nx) out_UV[i+1].u += 1.0f; if (out_UV[i+1].u - out_UV[i].u &gt; nx) out_UV[i].u += 1.0f; if (out_UV[i].u - out_UV[i+2].u &gt; nx) out_UV[i+2].u += 1.0f; if (out_UV[i+2].u - out_UV[i].u &gt; nx) out_UV[i].u += 1.0f; if (out_UV[i+1].u - out_UV[i+2].u &gt; nx) out_UV[i+2].u += 1.0f; if (out_UV[i+2].u - out_UV[i+1].u &gt; nx) out_UV[i+1].u += 1.0f; if (out_UV[i].v - out_UV[i+1].v &gt; nv) out_UV[i+1].v += 1.0f; if (out_UV[i+1].v - out_UV[i].v &gt; nv) out_UV[i].v += 1.0f; if (out_UV[i].v - out_UV[i+2].v &gt; nv) out_UV[i+2].v += 1.0f; if (out_UV[i+2].v - out_UV[i].v &gt; nv) out_UV[i].v += 1.0f; if (out_UV[i+1].v - out_UV[i+2].v &gt; nv) out_UV[i+2].v += 1.0f; if (out_UV[i+2].v - out_UV[i+1].v &gt; nv) out_UV[i+1].v += 1.0f; } </code></pre>
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