1 files changed, 36 insertions, 23 deletions

diff --git a/src/libjin/Graphics/Canvas.cpp b/src/libjin/Graphics/Canvas.cpp
index 4def58d..efcd12d 100644
--- a/src/libjin/Graphics/Canvas.cpp
+++ b/src/libjin/Graphics/Canvas.cpp
@@ -10,13 +10,19 @@ namespace jin
 namespace graphics
 {
 
-    /*class member*/ GLint Canvas::cur = -1;
+    /*class member*/ const Canvas* Canvas::current = nullptr;
+    /*class member*/ const Canvas* const Canvas::DEFAULT_CANVAS = new Canvas(0);
 
     /*class member*/ Canvas* Canvas::createCanvas(int w, int h)
     {
         return new Canvas(w, h);
     }
 
+    Canvas::Canvas(GLuint n) 
+        : fbo(n)
+    {
+    }
+
     Canvas::Canvas(int w, int h) 
         : Drawable(w, h)
     {
@@ -56,63 +62,70 @@ namespace graphics
     {
     }
 
-    bool Canvas::hasbind(GLint fbo)
+    /*class member*/ bool Canvas::isBinded(const Canvas* cvs)
     {
-        return cur == fbo; 
+        return current == cvs;
     }
 
     /**
     * bind to canvas 
     */
-    void Canvas::bind()
+    /*class member*/ void Canvas::bind(Canvas* canvas)
     {
-        if (hasbind(fbo)) return;
-
-        cur = fbo;
+        if (isBinded(canvas)) return;
+        current = canvas;
+        glBindFramebuffer(GL_FRAMEBUFFER, canvas->fbo);
 
-        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+        int w = canvas->size.w; 
+        int h = canvas->size.h;
+        /* set view port to canvas */
+        glViewport(0, 0, w, h);
 
+        /* set projection matrix */
         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         glLoadIdentity();
+        glOrtho(0, w, h, 0, -1, 1);
 
-        glViewport(0, 0, size.w, size.h);
-        glOrtho(0, size.w, size.h, 0, -1, 1);
-
-        /* Switch back to modelview matrix */
+        /* set (model*view) matrix */
         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();
         glLoadIdentity();
+
+        /* ready to draw */
     }
 
     /**
     * bind to default screen render buffer. 
+    * do some coordinates transform work
+    * https://blog.csdn.net/liji_digital/article/details/79370841
+    * https://blog.csdn.net/lyx2007825/article/details/8792475
     */
     /*class member*/ void Canvas::unbind()
     {
-        if (hasbind(0)) return;
-        
-        cur = 0;
-
-        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+        if (isBinded(DEFAULT_CANVAS)) return;
+        current = DEFAULT_CANVAS;
+        /* get window size as viewport */
         Window* wnd = Window::get();
         int ww = wnd->getW();
         int wh = wnd->getH();
 
-        glViewport(0, 0, ww, wh);
+        glBindFramebuffer(GL_FRAMEBUFFER, DEFAULT_CANVAS->fbo);
 
-        /* load back to normal */
+        glViewport(0, 0, ww, wh);
+        
+        /* set projection matrix */
         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         glLoadIdentity();
-        
-        /* set viewport matrix */
         glOrtho(0, ww, wh, 0, -1, 1);
-
-        /*  switch to model matrix */ 
+        
+        /* set (model*view) matrix */ 
         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();
         glLoadIdentity();
+
+        /* ready to draw */
     }
 
 } // render