Changes between Version 10 and Version 11 of tutorial

Timestamp:

Jun 27, 2013, 12:38:41 AM (12 years ago)

Author:

leon

Comment:

Ex2

tutorial

@@ -132 +132 @@
 
 == Modern OpenGL ==
-Create {{{triangle.c}}} and update {{{Makefile}}} [[Image(triangle.png,right)]]
+[[Image(triangle.png,right)]]
 We extend previous exercise with example that introduces OpenGL 3.x techniques:
- * OpenGL Shading Language 
+ * OpenGL Shading Language where simple vertex and fragment shader are required.
  * Vertex Buffer Objects stored in GPU
-
+Create {{{triangle.c}}} and update {{{Makefile}}} with new target
 {{{
 #!sh
@@ -229 +229 @@
 }
 }}}
+
+== 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:
+   {{{
+   #!c
+    GLint compiled;
+    glGetShaderiv(v, GL_COMPILE_STATUS, &compiled );
+    if ( !compiled ) {
+      GLsizei len;
+      glGetShaderiv( v, GL_INFO_LOG_LENGTH, &len );
+      GLchar* log = malloc(sizeof(GLchar)*(len+1));
+      printf("Shader compilation failed: %s\n", log);
+      free(log);
+    }
+   }}}
+ Do not forget to repeat the same thing for fragment shader.
+ 2. Add linker debugging
+   {{{
+   #!c  
+    GLint linked;
+    glGetProgramiv(p, GL_LINK_STATUS, &linked );
+    if ( !linked ) {
+      GLsizei len;
+      glGetProgramiv( p, GL_INFO_LOG_LENGTH, &len );
+      GLchar* log = malloc(sizeof(GLchar)*(len+1));
+      glGetProgramInfoLog( p, len, &len, log );
+      printf("Shader linking failed: %s\n", log);
+      free(log);
+    }
+   }}}
+  3. For general (core) OpenGL errors we can use the following utility at suspicious places.
+  {{{
+  #!c
+     GLenum errCode;
+     if ((errCode = glGetError()) != GL_NO_ERROR) {
+        const GLubyte *errString = gluErrorString(errCode);
+        fprintf (stderr, "OpenGL Error: %s\n", errString);
+     }
+  }}}