updated makefile for supporting different target architectures

use "ARCH=arch_name make"

restructured project folder, implementations and headers together under sources/

sources/GL_STUFF/GLES_3_1_compatibility.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <GLES2/gl2.h>
+
+/* fails at link time, 
+resorting to eglGetProcAddress
+
+#define GL_GLEXT_PROTOTYPES 1
+*/
+#include <GLES2/gl2ext.h>
+
+/* aarch64-linux-gnu/include/math.h already defines it */
+#ifndef M_PI
+#define M_PI	3.14159265358979323846264338327950288
+#endif
+
+/* GLES2 provides it as an extension */
+#ifndef GL_DEPTH24_STENCIL8
+#define GL_DEPTH24_STENCIL8 GL_DEPTH24_STENCIL8_OES
+#endif
+
+#ifndef GL_DEPTH_STENCIL_ATTACHMENT
+#define GL_DEPTH_STENCIL_ATTACHMENT GL_DEPTH_STENCIL_OES
+#endif
+
+#ifndef GL_DRAW_FRAMEBUFFER
+#define GL_DRAW_FRAMEBUFFER GL_DRAW_BUFFER0_EXT
+#endif
+
+void glGenVertexArrays( GLuint n, GLuint *arrays_ptr);
+
+void glBindVertexArray( GLuint array_ptr);
+
+void glDrawBuffers( GLsizei n,GLenum *buffers_ptr);
+
+void GLES_3_1_comp_init();
+
+#ifdef __cplusplus
+}
+#endif