When SDL is used with OpenGL, the UV coordinates of OpenGL textures are reversed up and down.

Write by nine days Yan Ling (jtianling) -- blog.csdn.net/vagrxie

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Same paragraphProgramIn SDL with OpenGL, it is correct when glfw is used and Windows API is used to add OpenGL.
As follows:
Glbegin (gl_quads );
Gltexcoord2f (0.0, 0.0); glvertex3f (-1.0,-1.0, 0.0 );
Gltexcoord2f (1.0, 0.0); glvertex3f (1.0,-1.0, 0.0 );
Gltexcoord2f (1.0, 1.0); glvertex3f (1.0, 1.0, 0.0 );
Gltexcoord2f (0.0, 1.0); glvertex3f (-1.0, 1.0, 0.0 );
Glend ();

By default, the origin of the UV coordinate of the texture is in the lower left corner, which is in the upper left corner by default in SDL. Therefore, you need to reverse the coordinate Y axis of the texture above, this shows that there is no problem. As shown below:
Glbegin (gl_quads );
Gltexcoord2f (0.0, 1.0); glvertex3f (-1.0,-1.0, 0.0 );
Gltexcoord2f (1.0, 1.0); glvertex3f (1.0,-1.0, 0.0 );
Gltexcoord2f (1.0, 0.0); glvertex3f (1.0, 1.0, 0.0 );
Gltexcoord2f (0.0, 0.0); glvertex3f (-1.0, 1.0, 0.0 );
Glend ();

 

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Write by nine days Yan Ling (jtianling) -- blog.csdn.net/vagrxie