ZImage miniscule changes

changelog.txt

@@ -1,5 +1,5 @@
-ZEngine Version Log for Version 0.8.4
+ZEngine Version Log for Version 0.8.5
-$Id: changelog.txt,v 1.43 2003/08/31 22:15:00 cozman Exp $
+$Id: changelog.txt,v 1.44 2003/09/05 19:44:13 cozman Exp $
 
 Changes are marked with symbols that describe them:
 ! is code that breaks backwards compatibility (used after 0.8.0-rc1, previous versions broke compatibility)
@@ -9,9 +9,11 @@ Changes are marked with symbols that describe them:
 # general changes
 
 0.8.5
-    + Addition of limited SDL graphics backend.
+    + Addition of DrawClipped and DrawClipped example in ZImageTest
+    + New limited SDL graphics backend for platforms without OpenGL.
     - Removal of VC6 project files and official support.
     - Removal of SDL_net support. 
+    # Tiny optimizations within newer ZImage code.
     # Changed ZImage stretching to floating-point.
     # New linux build system (by Atani).
 

include/ZE_Defines.h

@@ -13,7 +13,7 @@
     \brief Define file for ZEngine where all #define statements to control compilation options are placed.
 
     Definition file, holds #define statements describing optional features of ZEngine.
-    <br>$Id: ZE_Defines.h,v 1.22 2003/08/08 04:24:42 cozman Exp $<br>
+    <br>$Id: ZE_Defines.h,v 1.23 2003/09/05 19:44:13 cozman Exp $<br>
     \author James Turk
 **/
 
@@ -22,7 +22,6 @@
 
 //Defines- undefine any of these if you dont have the indicated SDL extension//
 
-
 //! OpenGL 2D Rendering Target.
 #define ZE_OGL (1)
 //! SDL Rendering Target.

include/ZE_ZImage.h

@@ -13,7 +13,7 @@
     \brief Definition file for ZImage.
 
     Definition file for ZImage, the OpenGL version of the ZImage class for ZEngine.
-    <br>$Id: ZE_ZImage.h,v 1.24 2003/09/01 03:30:39 cozman Exp $<br>
+    <br>$Id: ZE_ZImage.h,v 1.25 2003/09/05 19:44:13 cozman Exp $<br>
     \author James Turk
 **/
 
@@ -216,9 +216,11 @@ class ZImage
         void Draw(int x, int y) const;
 
         /*!
-            \brief Draw Clipped Image to screen.
+            \brief Draw Image, clipped within a given rectangle to the screen.
 
-            Image is drawn such that only portions of image which fall within a certain area appear.
+            Image is drawn such that only portions of image which fall within a certain area appear.  This clipping rectangle
+            can be used for areas of the screen which are separated from others such as a splitscreen mode in a game or a 
+            map on a HUD.
             \since 0.8.5
             \param x X coord to draw Image to.
             \param y Y coord to draw Image to.
@@ -259,9 +261,11 @@ class ZImage
         void DrawRotated(float x, float y, float angle) const;
 
         /*!
-            \brief Draw Clipped Image to screen.
+            \brief Draw Image, clipped within a given rectangle to the screen.
 
-            Image is drawn such that only portions of image which fall within a certain area appear.
+            Image is drawn such that only portions of image which fall within a certain area appear.  This clipping rectangle
+            can be used for areas of the screen which are separated from others such as a splitscreen mode in a game or a 
+            map on a HUD.
             \since 0.8.5
             \param x X coord to draw Image to.
             \param y Y coord to draw Image to.

src/ZE_ZImage.cpp

@@ -13,7 +13,7 @@
     \brief Source file for ZImage.
 
     Implementation of ZImage, the Image class for ZEngine.
-    <br>$Id: ZE_ZImage.cpp,v 1.44 2003/09/01 06:01:34 cozman Exp $<br>
+    <br>$Id: ZE_ZImage.cpp,v 1.45 2003/09/05 19:44:13 cozman Exp $<br>
     \author James Turk
 **/
 
@@ -244,10 +244,7 @@ void ZImage::DrawRotated(float x, float y, float angle) const
 
 void ZImage::DrawClipped(float x, float y, ZRect clipRect) const
 {
-    ZRect imgRect(x,y,rWidth,rHeight),inRect;
+    ZRect imgRect(x,y,rWidth,rHeight);
-    float xDiff,yDiff,nx,ny,nw,nh;
-    xDiff = rTexMaxX - rTexMinX;
-    yDiff = rTexMaxY - rTexMinY;
 
     if(clipRect.Contains(imgRect))
     {
@@ -255,20 +252,30 @@ void ZImage::DrawClipped(float x, float y, ZRect clipRect) const
     }
     else if(clipRect.Intersects(imgRect))
     {
-        inRect = clipRect.Intersection(imgRect);
+        //This is some pretty complex code, it is broken down in 4 steps. 
 
-        nx = rTexMinX + (inRect.X()-imgRect.X())/imgRect.Width()*xDiff;
+        //Step 1: The intersection rectangle (inRect) is compared to the image rectangle and the overlapping area is found. 
-        ny = rTexMinY + (inRect.Y()-imgRect.Y())/imgRect.Height()*yDiff;
+        ZRect inRect = clipRect.Intersection(imgRect); 
-        nw = nx + (inRect.Width()/imgRect.Width())*xDiff;
-        nh = ny + (inRect.Height()/imgRect.Height())*yDiff;
 
-        glColor4ub(255,255,255,rAlpha); //sets the color correctly
+        //Step 2: The portion of the image that needs to be drawn is being mapped to triangle strips the same size as the intersection
+        //        of the clipping and image rectangles and then transformed to texture coordinates via xScale and yScale.
+        //        (double is used for needed precision when dealing with the scaling)
+        double xScale = (rTexMaxX - rTexMinX)*rWidth;   //texCoordWidth/imgWidth
+        double yScale = (rTexMaxY - rTexMinY)*rHeight;  //texCoordHeight/imgHeight
+        double nx = rTexMinX + (inRect.X()-x)/xScale;    //cut off left side
+        double ny = rTexMinY + (inRect.Y()-y)/yScale;    //cut off top
+        double nw = nx + inRect.Width()/xScale;      //cut off right side
+        double nh = ny + inRect.Height()/yScale;     //cut off bottom
+
+        glColor4ub(255,255,255,rAlpha);
         Bind();
         glBegin(GL_TRIANGLE_STRIP);
-            glTexCoord2f(nx,ny);    glVertex2f(inRect.Left(),inRect.Top());
+            //Step 3: The texture coords are modified to only specify the portion of the texture which falls within the clipping rect.
-            glTexCoord2f(nw,ny);    glVertex2f(inRect.Right(),inRect.Top());
+            //Step 4: The vertices are changed to the sides of the clipping rectangle in glVertex2f.
-            glTexCoord2f(nx,nh);    glVertex2f(inRect.Left(),inRect.Bottom());
+            glTexCoord2d(nx,ny);  glVertex2f(inRect.Left(),inRect.Top());
-            glTexCoord2f(nw,nh);    glVertex2f(inRect.Right(),inRect.Bottom());
+            glTexCoord2d(nw,ny);  glVertex2f(inRect.Right(),inRect.Top());
+            glTexCoord2d(nx,nh);  glVertex2f(inRect.Left(),inRect.Bottom());
+            glTexCoord2d(nw,nh);  glVertex2f(inRect.Right(),inRect.Bottom());
         glEnd();
         glColor4ub(255,255,255,255);    //be responsible, return to standard color state
     }
@@ -280,21 +287,11 @@ void ZImage::DrawClipped(float x, float y, ZRect clipRect) const
 
 void ZImage::Flip(bool horizontal, bool vertical)
 {
-    GLfloat temp;
     //all that a flip does is invert the Min/Max coordinates
     if(horizontal)
-    {
+        std::swap(rTexMinX,rTexMaxX);
-        temp = rTexMinX;
-        rTexMinX = rTexMaxX;
-        rTexMaxX = temp;
-    }
-
     if(vertical)
-    {
+        std::swap(rTexMinY,rTexMaxY);
-        temp = rTexMinY;
-        rTexMinY = rTexMaxY;
-        rTexMaxY = temp;
-    }
 }
 
 //stretching and resizing is very inexpensive, done via variables

test/ZImageTest.cpp

@@ -9,7 +9,7 @@ This example file is in the public domain, it may be used with no restrictions.
      and the home of this Library is http://www.zengine.sourceforge.net
 *******************************************************************************/
 
-/*$Id: ZImageTest.cpp,v 1.22 2003/09/01 06:01:06 cozman Exp $*/
+/*$Id: ZImageTest.cpp,v 1.23 2003/09/05 19:44:13 cozman Exp $*/
 
 #include <ZEngine.h>
 #include <string> 
@@ -55,12 +55,13 @@ void Test()
     image1.Attach(temp);    //this attaches the surface into itself
     image2.Open("data/test01.bmp");
     image3.OpenFromImage(image2.Surface(),5,5,20,20);
-    image4.Open("data/rainbow.bmp");
+    image4.Open("data/test02.bmp");
     temp = NULL;    //and temp will now be controlled and freed by image1
     image1.SetColorKey(255,0,255);
     image2.SetColorKey(255,0,255);
 #if (GFX_BACKEND == ZE_OGL)
     image4.Resize(400,300);
+    image4.Flip(true,false);
 #endif
     font.DrawShadedText("ZImage Test.",textImage);