allow overriding a gl function with the same name, and keep the original accessible through getProcAddress

3 files changed, 205 insertions, 7 deletions

diff --git a/src/library_gl.js b/src/library_gl.js
index dc1c1fc6..c134ad97 100644
--- a/src/library_gl.js
+++ b/src/library_gl.js
@@ -4319,15 +4319,28 @@ LibraryGL.emscripten_GetProcAddress__deps = [function() {
   // ProcAddress is used, so include everything in GL. This runs before we go to the $ProcAddressTable object,
   // and we fill its deps just in time, and create the lookup table
   var table = {};
-  LibraryManager.library.emscripten_procAddressTable__deps = keys(LibraryGL).filter(function(x) {
-    if (x.substr(-6) == '__deps' || x.substr(-9) == '__postset' || x.substr(-5) == '__sig' || x.substr(0, 2) != 'gl') return false;
-    var sig = LibraryGL[x + '__sig'] || functionStubSigs['_' + x];
+  LibraryManager.library.emscripten_procAddressTable__deps = keys(LibraryGL).map(function(x) {
+    if (x.substr(-6) == '__deps' || x.substr(-9) == '__postset' || x.substr(-5) == '__sig' || x.substr(-5) == '__asm' || x.substr(0, 2) != 'gl') return null;
+    var original = x;
+    if (('_' + x) in Functions.implementedFunctions) {
+      // a user-implemented function aliases this one, but we still want it to be accessible by name, so rename it
+      var y = x + '__procTable';
+      LibraryManager.library[y] = LibraryManager.library[x];
+      LibraryManager.library[y + '__deps'] = LibraryManager.library[x + '__deps'];
+      LibraryManager.library[y + '__postset'] = LibraryManager.library[x + '__postset'];
+      LibraryManager.library[y + '__sig'] = LibraryManager.library[x + '__sig'];//|| Functions.implementedFunctions['_' + x];
+      LibraryManager.library[y + '__asm'] = LibraryManager.library[x + '__asm'];
+      x = y;
+      assert(!(y in Functions.implementedFunctions) && !Functions.unimplementedFunctions['_' + y]);
+    }
+    var longX = '_' + x;
+    var sig = LibraryManager.library[x + '__sig'] || functionStubSigs[longX];
     if (sig) {
-      table[x] = Functions.getIndex('_' + x, sig);
-      if (!(('_' + x) in Functions.implementedFunctions)) Functions.unimplementedFunctions[('_' + x)] = sig;
+      table[original] = Functions.getIndex(longX, sig);
+      if (!(longX in Functions.implementedFunctions)) Functions.unimplementedFunctions[longX] = sig;
     }
-    return true;
-  });
+    return x;
+  }).filter(function(x) { return x !== null });
   // convert table into function with switch, to not confuse closure compiler
   var tableImpl = 'switch(name) {\n';
   for (var x in table) tableImpl += 'case "' + x + '": return ' + table[x] + '; break;\n';
diff --git a/tests/sdl_ogl_proc_alias.c b/tests/sdl_ogl_proc_alias.c
new file mode 100644
index 00000000..c96da81b
--- /dev/null
+++ b/tests/sdl_ogl_proc_alias.c
@@ -0,0 +1,180 @@
+/*******************************************************************
+ *                                                                 *
+ *                        Using SDL With OpenGL                    *
+ *                                                                 *
+ *                    Tutorial by Kyle Foley (sdw)                 *
+ *                                                                 *
+ * http://gpwiki.org/index.php/SDL:Tutorials:Using_SDL_with_OpenGL *
+ *                                                                 *
+ *******************************************************************/
+
+/*
+THIS WORK, INCLUDING THE SOURCE CODE, DOCUMENTATION
+AND RELATED MEDIA AND DATA, IS PLACED INTO THE PUBLIC DOMAIN.
+
+THE ORIGINAL AUTHOR IS KYLE FOLEY.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+#include "SDL/SDL.h"
+#include "SDL/SDL_image.h"
+#include "SDL/SDL_opengl.h"
+
+#include <stdio.h>
+#include <string.h>
+
+void (*true_glGenTextures)(GLsizei, GLuint*) = NULL;
+
+void glGenTextures(GLsizei n, GLuint *textures) {
+  printf("num? %d\n", n);
+  true_glGenTextures(n + 1, textures); // correct the error, ensures we are gone through
+}
+
+int main(int argc, char *argv[])
+{
+    SDL_Surface *screen;
+
+    // Slightly different SDL initialization
+    if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
+        printf("Unable to initialize SDL: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*
+
+    screen = SDL_SetVideoMode( 640, 480, 16, SDL_OPENGL ); // *changed*
+    if ( !screen ) {
+        printf("Unable to set video mode: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    // Set the OpenGL state after creating the context with SDL_SetVideoMode
+
+    glClearColor( 0, 0, 0, 0 );
+
+    glEnable( GL_TEXTURE_2D ); // Needed when we're using the fixed-function pipeline.
+
+    glViewport( 0, 0, 640, 480 );
+
+    glMatrixMode( GL_PROJECTION );
+    glPushMatrix(); // just for testing
+    glLoadIdentity();
+
+    glOrtho( 0, 640, 480, 0, -1, 1 );
+
+    glMatrixMode( GL_MODELVIEW );
+    glLoadIdentity();
+
+    // Load the OpenGL texture
+
+    GLuint texture; // Texture object handle
+    SDL_Surface *surface; // Gives us the information to make the texture
+
+    if ( (surface = IMG_Load("screenshot.png")) ) {
+
+        // Check that the image's width is a power of 2
+        if ( (surface->w & (surface->w - 1)) != 0 ) {
+            printf("warning: image.bmp's width is not a power of 2\n");
+        }
+
+        // Also check if the height is a power of 2
+        if ( (surface->h & (surface->h - 1)) != 0 ) {
+            printf("warning: image.bmp's height is not a power of 2\n");
+        }
+
+        true_glGenTextures = SDL_GL_GetProcAddress("glGenTextures");
+
+        // Have OpenGL generate a texture object handle for us
+        glGenTextures( 0, &texture );
+
+        // Bind the texture object
+        glBindTexture( GL_TEXTURE_2D, texture );
+
+        // Set the texture's stretching properties
+        glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
+        glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
+
+        //SDL_LockSurface(surface);
+
+        // Add some greyness
+        memset(surface->pixels, 0x66, surface->w*surface->h);
+
+        // Edit the texture object's image data using the information SDL_Surface gives us
+        glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, surface->w, surface->h, 0,
+                      GL_RGBA, GL_UNSIGNED_BYTE, surface->pixels );
+
+        //SDL_UnlockSurface(surface);
+    }
+    else {
+        printf("SDL could not load image.bmp: %s\n", SDL_GetError());
+        SDL_Quit();
+        return 1;
+    }
+
+    // Free the SDL_Surface only if it was successfully created
+    if ( surface ) {
+        SDL_FreeSurface( surface );
+    }
+
+    // Clear the screen before drawing
+    glClear( GL_COLOR_BUFFER_BIT );
+
+    // Bind the texture to which subsequent calls refer to
+    glBindTexture( GL_TEXTURE_2D, texture );
+
+    glBegin( GL_QUADS );
+        glTexCoord2i( 0, 0 ); glVertex3f( 10, 10, 0 );
+        glTexCoord2i( 1, 0 ); glVertex3f( 300, 10, 0 );
+        glTexCoord2i( 1, 1 ); glVertex3f( 300, 128, 0 );
+        glTexCoord2i( 0, 1 ); glVertex3f( 10, 128, 0 );
+
+        glTexCoord2f( 0, 0.5 ); glVertex3f( 410, 10, 0 );
+        glTexCoord2f( 1, 0.5 ); glVertex3f( 600, 10, 0 );
+        glTexCoord2f( 1, 1   ); glVertex3f( 630, 200, 0 );
+        glTexCoord2f( 0.5, 1 ); glVertex3f( 310, 250, 0 );
+    glEnd();
+
+    glBegin( GL_TRIANGLE_STRIP );
+        glTexCoord2i( 0, 0 ); glVertex3f( 100, 300, 0 );
+        glTexCoord2i( 1, 0 ); glVertex3f( 300, 300, 0 );
+        glTexCoord2i( 1, 1 ); glVertex3f( 300, 400, 0 );
+        glTexCoord2i( 0, 1 ); glVertex3f( 500, 410, 0 );
+    glEnd();
+
+    glDisable(GL_TEXTURE_2D);
+
+    glColor3ub(90, 255, 255);
+    glBegin( GL_QUADS );
+        glVertex3f( 10, 410, 0 );
+        glVertex3f( 300, 410, 0 );
+        glVertex3f( 300, 480, 0 );
+        glVertex3f( 10, 470, 0 );
+    glEnd();
+
+    glBegin( GL_QUADS );
+        glColor3f(1.0, 0, 1.0);   glVertex3f( 410, 410, 0 );
+        glColor3f(0, 1.0, 0);     glVertex3f( 600, 410, 0 );
+        glColor3f(0, 0, 1.0);     glVertex3f( 600, 480, 0 );
+        glColor3f(1.0, 1.0, 1.0); glVertex3f( 410, 470, 0 );
+    glEnd();
+
+    SDL_GL_SwapBuffers();
+
+#if !EMSCRIPTEN
+    // Wait for 3 seconds to give us a chance to see the image
+    SDL_Delay(3000);
+#endif
+
+    // Now we can delete the OpenGL texture and close down SDL
+    glDeleteTextures( 1, &texture );
+
+    SDL_Quit();
+
+    return 0;
+}
diff --git a/tests/test_browser.py b/tests/test_browser.py
index 323677ba..69fb6f7e 100644
--- a/tests/test_browser.py
+++ b/tests/test_browser.py
@@ -859,6 +859,11 @@ Press any key to continue.'''
       args=['--preload-file', 'screenshot.png', '-s', 'LEGACY_GL_EMULATION=1'],
       message='You should see an image with gray at the top.')
 
+  def test_sdl_ogl_proc_alias(self):
+    shutil.copyfile(path_from_root('tests', 'screenshot.png'), os.path.join(self.get_dir(), 'screenshot.png'))
+    self.btest('sdl_ogl_proc_alias.c', reference='screenshot-gray-purple.png', reference_slack=1,
+               args=['-O2', '-g2', '-s', 'INLINING_LIMIT=1', '--preload-file', 'screenshot.png', '-s', 'LEGACY_GL_EMULATION=1', '-s', 'VERBOSE=1'])
+
   def test_sdl_fog_simple(self):
     shutil.copyfile(path_from_root('tests', 'screenshot.png'), os.path.join(self.get_dir(), 'screenshot.png'))
     self.btest('sdl_fog_simple.c', reference='screenshot-fog-simple.png',