Changes between Version 18 and Version 19 of tutorial

Timestamp:

Jun 28, 2013, 10:02:05 PM (11 years ago)

Author:

leon

Comment:

Add zoomin/out

tutorial

@@ -100 +100 @@
 
 
-== Exercises #1: ==
+=== Exercises #1: ===
  1. Add RGB color to vertices with {{{ glColor3f(0.0, 0.4, 1.0);}}}.
  2. Replace single line drawing in {{{display()}}} with the following snippet
@@ -251 +251 @@
 }}}
 [[Image(triangle.png,align=bottom,right,title=Triangles )]]
-== Exercises #2 ==
+=== Exercises #2 ===
  1. To be able to continue and not get lost introduce shader compiler logs in case of compilation errors by adding the following code into {{{setShaders()}}} right at after vertex shader compilation:
    {{{
@@ -479 +479 @@
 }
 }}}
-
+=== Exercises #3 ===
+ 1. Introduce zoom in/out functionality of the viewer by adding mouse wheel events to the end of `mouse()`
+  {{{
+  #!c
+  if (button == 3 && state == GLUT_DOWN)
+    { zoom *= 1.1; glutPostRedisplay(); }
+  else if (button == 4 && state == GLUT_DOWN)
+    { zoom /= 1.1; glutPostRedisplay(); }
+  }}}
+  and introduction of global variable `float zoom = 1.0;` that is communicated to GPU by additional `uniform float Zoom;` in the `vertex_shader[]`. Last line is replaced by
+  {{{
+  #!c
+    gl_Position = gl_ProjectionMatrix * RotationMatrix \
+     * gl_ModelViewMatrix*vec4(Zoom*gl_Vertex.xyz, 1.0); \
+  }}}
+  In the `display()` we add zooming by
+  {{{
+  #!c
+   location = glGetUniformLocation(p, "Zoom");
+   if (location >= 0)  glUniform1f(location, zoom);
+  }}}
   
+
+
+