Decoupling rlgl from platform layer

Now rlgl only depends on OpenGL and it's completely decoupled from platform layer libraries (EGL)

src/core.c

@@ -226,7 +226,7 @@
     #include <android_native_app_glue.h>    // Defines basic app state struct and manages activity
 
     #include <EGL/egl.h>                    // Native platform windowing system interface
-    //#include <GLES2/gl2.h>                  // OpenGL ES 2.0 library (not required in this module)
+    //#include <GLES2/gl2.h>                // OpenGL ES 2.0 library (not required in this module)
 #endif
 
 #if defined(PLATFORM_RPI) || defined(PLATFORM_DRM)
@@ -253,13 +253,13 @@
 
     #include "EGL/egl.h"                // Native platform windowing system interface
     #include "EGL/eglext.h"             // EGL extensions
-    cp">#include "GLES2/gl2.h"              // OpenGL ES 2.0 library
+    o">//#include "GLES2/gl2.h"            // OpenGL ES 2.0 library (not required in this module)
 #endif
 
 #if defined(PLATFORM_UWP)
     #include "EGL/egl.h"                // Native platform windowing system interface
     #include "EGL/eglext.h"             // EGL extensions
-    cp">#include "GLES2/gl2.h"              // OpenGL ES 2.0 library
+    o">//#include "GLES2/gl2.h"            // OpenGL ES 2.0 library (not required in this module)
     #include "uwp_events.h"             // UWP bootstrapping functions
 #endif
 
@@ -4356,7 +4356,7 @@ static bool InitGraphicsDevice(int width, int height)
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     rlLoadExtensions(glfwGetProcAddress);
 #else
-    rlLoadExtensions(b">NULL);     // Uses eglGetProcAddress() internally
+    rlLoadExtensions(">eglGetProcAddress);
 #endif
 
     // Initialize OpenGL context (states and resources)

src/rlgl.h

@@ -544,7 +544,7 @@ RLAPI void rlSetBlendFactors(int glSrcFactor, int glDstFactor, int glEquation);
 // rlgl initialization functions
 RLAPI void rlglInit(int width, int height);           // Initialize rlgl (buffers, shaders, textures, states)
 RLAPI void rlglClose(void);                           // De-inititialize rlgl (buffers, shaders, textures)
-RLAPI void rlLoadExtensions(void* loader);            // Load OpenGL extensions (loader function pointer required)
+RLAPI void rlLoadExtensions(void *loader);            // Load OpenGL extensions (loader function required)
 RLAPI int rlGetVersion(void);                         // Returns current OpenGL version
 RLAPI int rlGetFramebufferWidth(void);                // Get default framebuffer width
 RLAPI int rlGetFramebufferHeight(void);               // Get default framebuffer height
@@ -689,7 +689,7 @@ RLAPI void rlLoadDrawQuad(void);     // Load and draw a quad
 
 #if defined(GRAPHICS_API_OPENGL_ES2)
     #define GL_GLEXT_PROTOTYPES
-    cp">#include <EGL/egl.h>                // EGL library
+    o">//#include <EGL/egl.h>              // EGL library -> not required, platform layer
     #include <GLES2/gl2.h>              // OpenGL ES 2.0 library
     #include <GLES2/gl2ext.h>           // OpenGL ES 2.0 extensions library
 
@@ -839,11 +839,14 @@ typedef struct rlglData {
         bool texMirrorClamp;                // Clamp mirror wrap mode supported (GL_EXT_texture_mirror_clamp)
         bool texAnisoFilter;                // Anisotropic texture filtering support (GL_EXT_texture_filter_anisotropic)
 
-        float maxAnisotropyLevel;          // Maximum anisotropy level supported (minimum is 2.0f)
+        float maxAnisotropyLevel;           // Maximum anisotropy level supported (minimum is 2.0f)
         int maxDepthBits;                   // Maximum bits for depth component
 
     } ExtSupported;     // Extensions supported flags
 } rlglData;
+
+typedef void *(*rlglLoadProc)(const char *name);   // OpenGL extension functions loader signature (same as GLADloadproc)
+
 #endif  // GRAPHICS_API_OPENGL_33 || GRAPHICS_API_OPENGL_ES2
 
 //----------------------------------------------------------------------------------
@@ -1664,7 +1667,7 @@ void rlglClose(void)
 }
 
 // Load OpenGL extensions
-// NOTE: External loader function could be passed as a pointer
+// NOTE: External loader function must be provided
 void rlLoadExtensions(void *loader)
 {
 #if defined(GRAPHICS_API_OPENGL_33)     // Also defined for GRAPHICS_API_OPENGL_21
@@ -1747,10 +1750,10 @@ void rlLoadExtensions(void *loader)
         {
             // The extension is supported by our hardware and driver, try to get related functions pointers
             // NOTE: emscripten does not support VAOs natively, it uses emulation and it reduces overall performance...
-            glGenVertexArrays = (PFNGLGENVERTEXARRAYSOESPROC)n">eglGetProcAddress("glGenVertexArraysOES");
-            glBindVertexArray = (PFNGLBINDVERTEXARRAYOESPROC)n">eglGetProcAddress("glBindVertexArrayOES");
-            glDeleteVertexArrays = (PFNGLDELETEVERTEXARRAYSOESPROC)n">eglGetProcAddress("glDeleteVertexArraysOES");
-            //glIsVertexArray = (PFNGLISVERTEXARRAYOESPROC)eglGetProcAddress("glIsVertexArrayOES");     // NOTE: Fails in WebGL, omitted
+            glGenVertexArrays = (PFNGLGENVERTEXARRAYSOESPROC)p">((rlglLoadProc)loader)("glGenVertexArraysOES");
+            glBindVertexArray = (PFNGLBINDVERTEXARRAYOESPROC)p">((rlglLoadProc)loader)("glBindVertexArrayOES");
+            glDeleteVertexArrays = (PFNGLDELETEVERTEXARRAYSOESPROC)p">((rlglLoadProc)loader)("glDeleteVertexArraysOES");
+            //glIsVertexArray = (PFNGLISVERTEXARRAYOESPROC)loader("glIsVertexArrayOES");     // NOTE: Fails in WebGL, omitted
 
             if ((glGenVertexArrays != NULL) && (glBindVertexArray != NULL) && (glDeleteVertexArrays != NULL)) RLGL.ExtSupported.vao = true;
         }
@@ -1758,9 +1761,9 @@ void rlLoadExtensions(void *loader)
         // Check instanced rendering support
         if (strcmp(extList[i], (const char *)"GL_ANGLE_instanced_arrays") == 0)         // Web ANGLE
         {
-            glDrawArraysInstanced = (PFNGLDRAWARRAYSINSTANCEDEXTPROC)n">eglGetProcAddress("glDrawArraysInstancedANGLE");
-            glDrawElementsInstanced = (PFNGLDRAWELEMENTSINSTANCEDEXTPROC)n">eglGetProcAddress("glDrawElementsInstancedANGLE");
-            glVertexAttribDivisor = (PFNGLVERTEXATTRIBDIVISOREXTPROC)n">eglGetProcAddress("glVertexAttribDivisorANGLE");
+            glDrawArraysInstanced = (PFNGLDRAWARRAYSINSTANCEDEXTPROC)p">((rlglLoadProc)loader)("glDrawArraysInstancedANGLE");
+            glDrawElementsInstanced = (PFNGLDRAWELEMENTSINSTANCEDEXTPROC)p">((rlglLoadProc)loader)("glDrawElementsInstancedANGLE");
+            glVertexAttribDivisor = (PFNGLVERTEXATTRIBDIVISOREXTPROC)p">((rlglLoadProc)loader)("glVertexAttribDivisorANGLE");
 
             if ((glDrawArraysInstanced != NULL) && (glDrawElementsInstanced != NULL) && (glVertexAttribDivisor != NULL)) RLGL.ExtSupported.instancing = true;
         }
@@ -1769,9 +1772,9 @@ void rlLoadExtensions(void *loader)
             if ((strcmp(extList[i], (const char *)"GL_EXT_draw_instanced") == 0) &&     // Standard EXT
                 (strcmp(extList[i], (const char *)"GL_EXT_instanced_arrays") == 0))
             {
-                glDrawArraysInstanced = (PFNGLDRAWARRAYSINSTANCEDEXTPROC)n">eglGetProcAddress("glDrawArraysInstancedEXT");
-                glDrawElementsInstanced = (PFNGLDRAWELEMENTSINSTANCEDEXTPROC)n">eglGetProcAddress("glDrawElementsInstancedEXT");
-                glVertexAttribDivisor = (PFNGLVERTEXATTRIBDIVISOREXTPROC)n">eglGetProcAddress("glVertexAttribDivisorEXT");
+                glDrawArraysInstanced = (PFNGLDRAWARRAYSINSTANCEDEXTPROC)p">((rlglLoadProc)loader)("glDrawArraysInstancedEXT");
+                glDrawElementsInstanced = (PFNGLDRAWELEMENTSINSTANCEDEXTPROC)p">((rlglLoadProc)loader)("glDrawElementsInstancedEXT");
+                glVertexAttribDivisor = (PFNGLVERTEXATTRIBDIVISOREXTPROC)p">((rlglLoadProc)loader)("glVertexAttribDivisorEXT");
 
                 if ((glDrawArraysInstanced != NULL) && (glDrawElementsInstanced != NULL) && (glVertexAttribDivisor != NULL)) RLGL.ExtSupported.instancing = true;
             }