https://bugs.freedesktop.org/show_bug.cgi?id=101325
--- Comment #13 from Julien Isorce julien.isorce@gmail.com --- apitrace dump:
94 glShaderSource(shader = 2, count = 2, string = {"#version 150
#define PLATFORM_USES_ES2 0
#define PLATFORM_LINUX 1 ", " #if PLATFORM_USES_ES2 precision highp float; #else // #version 120 at the beginning is added in FSlateOpenGLShader::CompileShader() #extension GL_EXT_gpu_shader4 : enable #endif
varying vec2 textureCoordinate;
uniform sampler2D SplashTexture;
void main() { // OpenGL has 0,0 the "math" way vec2 tc = vec2(textureCoordinate.s, 1.0-textureCoordinate.t);
gl_FragColor = texture2D(SplashTexture, tc);
}"}, length = NULL)
So it does not look that GL_EXT_gpu_shader4 is really used. Also I wonder if you can configure UE4Editor to use egl/gles2 and see if it still hangs.