Fix error discarding fragments in our_gl

examples/TinyRenderer/our_gl.cpp

@@ -182,7 +182,7 @@ void triangle(mat<4,3,float> &clipc, IShader &shader, TGAImage &image, float *zb
             bool discard = shader.fragment(bc_clip, color);
             if (frag_depth<-shader.m_farPlane)
                 discard=true;
-            if (frag_depth>-shader.m_nearPlane)
+            if (frag_depth>shader.m_nearPlane)
                 discard=true;
 
             if (!discard) {