Extended Mac OS support of gl_draw() functions to old Apple hardware that does not

implement the GL_EXT_texture_rectangle extension.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10852 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 77 insertions, 57 deletions

diff --git a/src/gl_draw.cxx b/src/gl_draw.cxx
index 5bee68327..a3a08e54b 100644
--- a/src/gl_draw.cxx
+++ b/src/gl_draw.cxx
@@ -36,10 +36,6 @@
 #include "Xutf8.h"
 #endif
 
-#ifdef __APPLE__
-static int gl_scale = 1; // set to 2 for high resolution Fl_Gl_Window
-#endif
-
 /** Returns the current font's height */
 int   gl_height() {return fl_height();}
 /** Returns the current font's descent */
@@ -326,13 +322,22 @@ void gl_draw_image(const uchar* b, int x, int y, int w, int h, int d, int ld) {
 }
 
 #if __APPLE__ || defined(FL_DOXYGEN)
+/* Text drawing to an OpenGL scene under Mac OS X is implemented using textures, as recommended by Apple.
+ This allows to use any font at any size, and any Unicode character.
+ Some old Apple hardware doesn't implement the required GL_EXT_texture_rectangle extension.
+ For these, glutStrokeString() is used to draw text. In that case, it's possible to vary text size,
+ but not text font, and only ASCII characters can be drawn.
+ */
 
 #if MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_4
 #define kCGBitmapByteOrder32Host 0
 #define GL_TEXTURE_RECTANGLE_ARB GL_TEXTURE_RECTANGLE_EXT
 #endif
+static int gl_scale = 1; // set to 2 for high resolution Fl_Gl_Window
+static int has_texture_rectangle = 0; // true means GL_EXT_texture_rectangle is available
 
-#include <FL/glu.h>  // for gluUnProject()
+#include <FL/glu.h>  // for gluUnProject() and gluCheckExtension()
+#include <FL/glut.H> // for glutStrokeString() and glutStrokeLength()
 
 // manages a fifo pile of pre-computed string textures
 class gl_texture_fifo {
@@ -343,14 +348,14 @@ private:
     char *utf8; //its text
     Fl_Font_Descriptor *fdesc; // its font
     int width; // its width
-    int height; // its height
+    float ratio; // used without rectangle texture
     int scale; // 1 or 2 for low/high resolution
   } data;
   data *fifo; // array of pile elements
   int size_; // pile height
   int current; // the oldest texture to have entered the pile
   int last; // pile top
-  int textures_generated; // true iff glGenTextures has been called
+  int textures_generated; // true after glGenTextures has been called
   void display_texture(int rank);
   int compute_texture(const char* str, int n);
   int already_known(const char *str, int n);
@@ -391,34 +396,44 @@ void gl_texture_fifo::display_texture(int rank)
   glLoadIdentity ();
   float winw = gl_scale * Fl_Window::current()->w();
   float winh = gl_scale * Fl_Window::current()->h();
-  glScalef (2.0f / winw, 2.0f /  winh, 1.0f);
-  glTranslatef (-winw / 2.0f, -winh / 2.0f, 0.0f);
-  //write the texture on screen
-  GLfloat pos[4];
-  glGetFloatv(GL_CURRENT_RASTER_POSITION, pos);
-  CGRect bounds = CGRectMake (pos[0], pos[1] - gl_scale*fl_descent(), fifo[rank].width, fifo[rank].height);
-  
   // GL_COLOR_BUFFER_BIT for glBlendFunc, GL_ENABLE_BIT for glEnable / glDisable
   glPushAttrib(GL_ENABLE_BIT | GL_TEXTURE_BIT | GL_COLOR_BUFFER_BIT); 
   glDisable (GL_DEPTH_TEST); // ensure text is not removed by depth buffer test.
   glEnable (GL_BLEND); // for text fading
   glBlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA); // ditto
-  glEnable (GL_TEXTURE_RECTANGLE_ARB);
   glDisable(GL_LIGHTING);
-  glBindTexture (GL_TEXTURE_RECTANGLE_ARB, fifo[rank].texName);
-  glBegin (GL_QUADS);
-  glTexCoord2f (0.0f, 0.0f); // draw lower left in world coordinates
-  glVertex2f (bounds.origin.x, bounds.origin.y);
-  
-  glTexCoord2f (0.0f, fifo[rank].height); // draw upper left in world coordinates
-  glVertex2f (bounds.origin.x, bounds.origin.y + bounds.size.height);
-  
-  glTexCoord2f (fifo[rank].width, fifo[rank].height); // draw upper right in world coordinates
-  glVertex2f (bounds.origin.x + bounds.size.width, bounds.origin.y + bounds.size.height);
-  
-  glTexCoord2f (fifo[rank].width, 0.0f); // draw lower right in world coordinates
-  glVertex2f (bounds.origin.x + bounds.size.width, bounds.origin.y);
-  glEnd ();
+  GLfloat pos[4];
+  glGetFloatv(GL_CURRENT_RASTER_POSITION, pos);
+  float R = 2;
+  if (!has_texture_rectangle) {
+    R *= fifo[rank].ratio;
+  }
+  glScalef (R/winw, R/winh, 1.0f);
+  glTranslatef (-winw/R, -winh/R, 0.0f);
+  if (has_texture_rectangle) {
+    glEnable (GL_TEXTURE_RECTANGLE_ARB);
+    glBindTexture (GL_TEXTURE_RECTANGLE_ARB, fifo[rank].texName);
+    GLint height;
+    glGetTexLevelParameteriv(GL_TEXTURE_RECTANGLE_ARB, 0, GL_TEXTURE_HEIGHT, &height);
+    CGRect bounds = CGRectMake (pos[0], pos[1] - gl_scale*fl_descent(), fifo[rank].width, height);
+    //write the texture on screen
+    glBegin (GL_QUADS);
+    glTexCoord2f (0.0f, 0.0f); // draw lower left in world coordinates
+    glVertex2f (bounds.origin.x, bounds.origin.y);
+    
+    glTexCoord2f (0.0f, height); // draw upper left in world coordinates
+    glVertex2f (bounds.origin.x, bounds.origin.y + bounds.size.height);
+    
+    glTexCoord2f (fifo[rank].width, height); // draw upper right in world coordinates
+    glVertex2f (bounds.origin.x + bounds.size.width, bounds.origin.y + bounds.size.height);
+    
+    glTexCoord2f (fifo[rank].width, 0.0f); // draw lower right in world coordinates
+    glVertex2f (bounds.origin.x + bounds.size.width, bounds.origin.y);
+    glEnd ();
+  } else {
+    glTranslatef(pos[0]*2/R, pos[1]*2/R, 0.0);
+    glutStrokeString(GLUT_STROKE_ROMAN, (uchar*)fifo[rank].utf8);
+  }
   glPopAttrib();
   
   // reset original matrices
@@ -445,41 +460,45 @@ int gl_texture_fifo::compute_texture(const char* str, int n)
 {
   current = (current + 1) % size_;
   if (current > last) last = current;
-  //write str to a bitmap just big enough  
   if ( fifo[current].utf8 ) free(fifo[current].utf8);
   fifo[current].utf8 = (char *)malloc(n + 1);
   memcpy(fifo[current].utf8, str, n);
   fifo[current].utf8[n] = 0;
-  fifo[current].width = 0, fifo[current].height = 0;
   fl_graphics_driver->font_descriptor(gl_fontsize);
-  fl_measure(fifo[current].utf8, fifo[current].width, fifo[current].height, 0);
+  int h;
+  fl_measure(fifo[current].utf8, fifo[current].width, h, 0);
   fifo[current].width *= gl_scale;
-  fifo[current].height *= gl_scale;
+  h *= gl_scale;
   fifo[current].scale = gl_scale;
-  CGColorSpaceRef lut = CGColorSpaceCreateDeviceRGB();
-  void *base = NULL;
-  if (fl_mac_os_version < 100600) base = calloc(4*fifo[current].width, fifo[current].height);
-  CGContextRef save_gc = fl_gc;
-  fl_gc = CGBitmapContextCreate(base, fifo[current].width, fifo[current].height, 8, fifo[current].width*4, lut,
-                                 (CGBitmapInfo)(kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
-  CGColorSpaceRelease(lut);
-  GLfloat colors[4];
-  glGetFloatv(GL_CURRENT_COLOR, colors);
-  fl_color((uchar)(colors[0]*255), (uchar)(colors[1]*255), (uchar)(colors[2]*255));
-  CGContextTranslateCTM(fl_gc, 0, fifo[current].height - gl_scale*fl_descent());
-  CGContextScaleCTM(fl_gc, gl_scale, gl_scale);
-  fl_draw(str, n, 0, 0);
-  //put this bitmap in a texture
-  glPushAttrib(GL_TEXTURE_BIT);
-  glBindTexture (GL_TEXTURE_RECTANGLE_ARB, fifo[current].texName);
-  glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-  glPixelStorei(GL_UNPACK_ROW_LENGTH, fifo[current].width);
-  glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8, fifo[current].width, fifo[current].height, 0,  GL_BGRA_EXT, GL_UNSIGNED_INT_8_8_8_8_REV, CGBitmapContextGetData(fl_gc));
-  glPopAttrib();
-  CGContextRelease(fl_gc);
-  fl_gc = save_gc;
-  if (base) free(base);
   fifo[current].fdesc = gl_fontsize;
+  if (has_texture_rectangle) {
+    //write str to a bitmap just big enough
+    CGColorSpaceRef lut = CGColorSpaceCreateDeviceRGB();
+    void *base = NULL;
+    if (fl_mac_os_version < 100600) base = calloc(4*fifo[current].width, h);
+    CGContextRef save_gc = fl_gc;
+    fl_gc = CGBitmapContextCreate(base, fifo[current].width, h, 8, fifo[current].width*4, lut,
+                                  (CGBitmapInfo)(kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
+    CGColorSpaceRelease(lut);
+    GLfloat colors[4];
+    glGetFloatv(GL_CURRENT_COLOR, colors);
+    fl_color((uchar)(colors[0]*255), (uchar)(colors[1]*255), (uchar)(colors[2]*255));
+    CGContextTranslateCTM(fl_gc, 0, h - gl_scale*fl_descent());
+    CGContextScaleCTM(fl_gc, gl_scale, gl_scale);
+    fl_draw(str, n, 0, 0);
+    //put this bitmap in a texture
+    glPushAttrib(GL_TEXTURE_BIT);
+    glBindTexture (GL_TEXTURE_RECTANGLE_ARB, fifo[current].texName);
+    glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glPixelStorei(GL_UNPACK_ROW_LENGTH, fifo[current].width);
+    glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8, fifo[current].width, h, 0,  GL_BGRA_EXT, GL_UNSIGNED_INT_8_8_8_8_REV, CGBitmapContextGetData(fl_gc));
+    glPopAttrib();
+    CGContextRelease(fl_gc);
+    fl_gc = save_gc;
+    if (base) free(base);
+  } else {
+    fifo[current].ratio = float(fifo[current].width)/glutStrokeLength(GLUT_STROKE_ROMAN, (uchar*)fifo[current].utf8);
+  }
   return current;
 }
 
@@ -503,7 +522,8 @@ static void gl_draw_textures(const char* str, int n)
   //fprintf(stderr,"gl_scale=%d\n",gl_scale);
   if (! gl_fifo) gl_fifo = new gl_texture_fifo();
   if (!gl_fifo->textures_generated) {
-    for (int i = 0; i < gl_fifo->size_; i++) glGenTextures (1, &(gl_fifo->fifo[i].texName));
+    has_texture_rectangle = gluCheckExtension((GLubyte*)"GL_EXT_texture_rectangle", glGetString(GL_EXTENSIONS));
+    if (has_texture_rectangle) for (int i = 0; i < gl_fifo->size_; i++) glGenTextures(1, &(gl_fifo->fifo[i].texName));
     gl_fifo->textures_generated = 1;
   }
   int rank = gl_fifo->already_known(str, n);