Working with UV coordinates when they are not in the range of 0 - 1

T Mason · 2014-07-16T02:02:34

Hello,I am using a loading library which supplies UV coordinates as shown below.Note that these coordinates are not in the range of 0.0 - 1.0Therefore the textures aren't mapping properly and the end results suck.I tried using GLSL's clamp as shown below in the fragment shader but that doesn't work.How do I work with these UV coordinates?Thank you for your time:GLSL shader snippet: MaterialTextureColor = texture2D(MainTextureSampler, clamp(TextureCoordinates, 0, 1)); UV Coordinates:Note that this is just a textual representation, the coordinates are floats within C++/OpenGL when loaded. UV Point: S: -53.0558 T: -15.3896 UV Point: S: 5.99937 T: -15.3896 UV Point: S: -3.84315 T: 2.00539 UV Point: S: -3.84315 T: 2.00539 UV Point: S: 5.99937 T: -15.3896 UV Point: S: 5.99937 T: 2.00539 UV Point: S: -53.0558 T: -15.3896 UV Point: S: -3.84315 T: 2.00539 UV Point: S: -53.0558 T: 4.29541 UV Point: S: -3.84315 T: 4.29541 UV Point: S: -53.0558 T: 4.29541 UV Point: S: -3.84315 T: 2.00539 UV Point: S: -3.84315 T: -2.00539 UV Point: S: -53.0558 T: -4.29541 UV Point: S: -3.84315 T: -4.29541 UV Point: S: -3.84315 T: -2.00539 UV Point: S: 5.99937 T: 15.3896 UV Point: S: -53.0558 T: 15.3896 UV Point: S: 5.99937 T: 15.3896 UV Point: S: -3.84315 T: -2.00539 UV Point: S: 5.99937 T: -2.00539 UV Point: S: -3.84315 T: -2.00539 UV Point: S: -53.0558 T: 15.3896 UV Point: S: -53.0558 T: -4.29541 UV Point: S: -2.00539 T: -0.492126 UV Point: S: 15.3896 T: -0.492126 UV Point: S: 15.3896 T: 3.75462e^-009 UV Point: S: 15.3896 T: 3.75462e^-009 UV Point: S: -2.00539 T: 3.75462e^-009 UV Point: S: -2.00539 T: -0.492126 UV Point: S: -3.84315 T: -0.492126 UV Point: S: 5.99937 T: -0.492126 UV Point: S: 5.99937 T: 3.75462e^-009 UV Point: S: 5.99937 T: 3.75462e^-009 UV Point: S: -3.84315 T: 3.75462e^-009 UV Point: S: -3.84315 T: -0.492126 UV Point: S: -4.29541 T: -0.492126 UV Point: S: -2.00539 T: -0.492126 UV Point: S: -2.00539 T: 3.75462e^-009 UV Point: S: -2.00539 T: 3.75462e^-009 UV Point: S: -4.29541 T: 3.75462e^-009 UV Point: S: -4.29541 T: -0.492126 UV Point: S: -53.0557 T: -0.492126 UV Point: S: -3.84315 T: -0.492126 UV Point: S: -53.0557 T: 3.75462e^-009 UV Point: S: -3.84315 T: 3.75462e^-009 UV Point: S: -53.0557 T: 3.75462e^-009 UV Point: S: -3.84315 T: -0.492126 UV Point: S: -15.3896 T: -0.492126 UV Point: S: 4.29541 T: -0.492126 UV Point: S: 4.29541 T: 3.75462e^-009 UV Point: S: 4.29541 T: 3.75462e^-009 UV Point: S: -15.3896 T: 3.75462e^-009 UV Point: S: -15.3896 T: -0.492126 UV Point: S: 5.99937 T: 0.492126 UV Point: S: -53.0558 T: 0.492126 UV Point: S: -53.0558 T: -3.75462e^-009 UV Point: S: -53.0558 T: -3.75462e^-009 UV Point: S: 5.99937 T: -3.75462e^-009 UV Point: S: 5.99937 T: 0.492126

Graphics and GPU Programming Programming OpenGL

Started by tmason July 09, 2014 11:52 AM

12 comments, last by Hodgman 9 years, 9 months ago

tmason

326

Author

July 13, 2014 08:43 PM

Hello!

Since the geometry data of your simple model seem to be correct, the texturing problem revealed by your final image may be caused by a faulty OpenGL code specifying this geometry (I think maybe somewhere in glTexCoord calls).

Thank you for your reply. I have created forum posts on AutoDESK's FBX SDK forums which is the library I use but they haven't replied back.

The code is based on their example so I will see if there is another example out there somewhere.

L. Spiro

25,818

July 13, 2014 10:24 PM

How did you print those new set of vertices?
The original UV’s you printed are very obviously not correct.
The second set has the correct values but in the wrong places.

Are you correctly indexing into the pools of normals, control points, and UV’s?
Because you know that there are 4 ways to determine which UV to use and the file can use any of them, and it appears that you have valid values, but mismatched between vertices (correct value, wrong place).

L. Spiro

I restore Nintendo 64 video-game OST’s into HD! https://www.youtube.com/channel/UCCtX_wedtZ5BoyQBXEhnVZw/playlists?view=1&sort=lad&flow=grid

tmason

326

Author

July 15, 2014 10:23 AM

How did you print those new set of vertices?
The original UV’s you printed are very obviously not correct.
The second set has the correct values but in the wrong places.

Are you correctly indexing into the pools of normals, control points, and UV’s?
Because you know that there are 4 ways to determine which UV to use and the file can use any of them, and it appears that you have valid values, but mismatched between vertices (correct value, wrong place).

L. Spiro

You hinted at the correct problem to solve.

I fixed this by actually setting the correct offset for my normals and UV's in the call to glVertexAttribPointer() and now everything works.

Thanks to everyone for all of your help.