Fix rendering: GL3+ needs VAO, initialize screen_width/screen_height

*yay* it works now *dances*

core/rend/gles/gldraw.cpp

@@ -904,8 +904,11 @@ void SetMVS_Mode(u32 mv_mode,ISP_Modvol ispc)
 	}
 }
 
+
 void SetupMainVBO()
 {
+	glBindVertexArray(gl.vbo.vao);
+
 	glBindBuffer(GL_ARRAY_BUFFER, gl.vbo.geometry); glCheck();
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gl.vbo.idxs); glCheck();
 
@@ -925,6 +928,8 @@ void SetupMainVBO()
 
 void SetupModvolVBO()
 {
+	glBindVertexArray(gl.vbo.vao);
+
 	glBindBuffer(GL_ARRAY_BUFFER, gl.vbo.modvols); glCheck();
 
 	//setup vertex buffers attrib pointers

core/rend/gles/gles.cpp

@@ -583,6 +583,12 @@ bool gl_init(void* hwnd, void* hdc)
 	if (rv) {
 		rv = gl3wInit() != -1 && gl3wIsSupported(3, 1);
 	}
+
+	RECT r;
+	GetClientRect((HWND)hwnd, &r);
+	screen_width = r.right - r.left;
+	screen_height = r.bottom - r.top;
+
 	return rv;
 }
 #include <Wingdi.h>
@@ -785,6 +791,14 @@ GLuint osd_font;
 
 bool gl_create_resources()
 {
+
+#ifndef GLES
+	//create vao
+	//This is really not "proper", vaos are suposed to be defined once
+	//i keep updating the same one to make the es2 code work in 3.1 context
+	glGenVertexArrays(1, &gl.vbo.vao);
+#endif
+
 	//create vbos
 	glGenBuffers(1, &gl.vbo.geometry);
 	glGenBuffers(1, &gl.vbo.modvols);

core/rend/gles/gles.h

@@ -26,7 +26,7 @@
 #endif
 
 
-#define glCheck() false
+#define glCheck() verify(glGetError()==GL_NO_ERROR)
 #define eglCheck() false
 
 #define VERTEX_POS_ARRAY 0
@@ -86,6 +86,9 @@ struct gl_ctx
 	struct
 	{
 		GLuint geometry,modvols,idxs,idxs2;
+#ifndef GLES
+		GLuint vao;
+#endif
 	} vbo;