Fix geometry clipping problem for GL ES.

NoN - no near clipping.
GL ES does not support z-clipping disabling, so harmless hack used here.
Harmlessness condition: z value is not used by pixel pipeline.
gDP.otherMode.depthCompare == 0 && gDP.otherMode.depthUpdate == 0 - z not used for depth compare/update.
Thus we can set vertex z to any value, which will ensure that z/w is in range [-1, 1], e.g. to zero.

Fixed issue #588

src/OpenGL.cpp

@@ -318,6 +318,15 @@ void OGLRender::addTriangle(int _v0, int _v1, int _v2)
 			vtx.z = gDP.primDepth.z * vtx.w;
 		}
 	}
+
+#ifdef GLESX
+	if (GBI.isNoN() && gDP.otherMode.depthCompare == 0 && gDP.otherMode.depthUpdate == 0) {
+		for (u32 i = triangles.num - 3; i < triangles.num; ++i) {
+			SPVertex & vtx = triangles.vertices[triangles.elements[i]];
+			vtx.z = 0.0f;
+		}
+	}
+#endif
 }
 
 void OGLRender::_setBlendMode() const