C / C++ / MFC

<pre>void OpenGL_Stencil(void (*Stencil)(int parameter)) {
	
// clear all three buffers - not neccessary
	glClear(GL_STENCIL_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//enable estecil test
	glEnable(GL_STENCIL_TEST);
// turn off writing to color buffer
	glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
// enable only to verify the stencil
//glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
// setup stencil function
	glStencilFunc(GL_ALWAYS, 1, 1);							// ??
// setup stencil opertion
	glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE);					// ??
// ??
	glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
// get stencil
// TDOD need parameter here
//OpenGL_Unit_Circle(0);
	Stencil(0);	// works with OpenGL_Unit_Circle(0) parameter
	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
//
this is where I am missing how to test the parameter 
	// switch keep area
	//Stencil->paramater == 0;
//	if (Stencil->paramater == 0)
		glStencilFunc(GL_EQUAL, 1, 1);		///keep inside circle
//	else
//		glStencilFunc(GL_NOTEQUAL, 1, 1);	 // keep all outside of stencil
//
	glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

void OpenGL_Stencil(void (*Stencil)(int))

void OpenGL_Stencil(void (*Stencil)(int), int value)

Stencil(value)

OpenGL_Stencil_Circle_Build(parameter);         returns parameter OK

OpenGL_Stencil(OpenGL_Stencil_Circle_Build(6)); wrong syntax

Description	Resource	Path	Location	Type
Invalid arguments '
Candidates are:
int OpenGL_Stencil(void (*)(int))
'	A_STENCIL.cpp	/A_STENCIL/src	line 766	Semantic Error
invalid conversion from ‘int’ to ‘void (*)(int)’ [-fpermissive]	A_STENCIL.cpp	/A_STENCIL/src	line 766	C/C++ Problem

invalid conversion from ‘int’ to ‘void (*)(int)

OpenGL_Stencil(OpenGL_Stencil_Circle_Build(6))

OpenGL_Stencil(OpenGL_Stencil_Circle_Build, 6)

void OpenGL_Stencil(void (*func) (int), int arg)
{
   //...
   func(arg);  // this is the line that will call OpenGL_Stencil_Circle_Build with a value of 6
}

Vaclav_ wrote:

Here is the entire test code

struct small_obj {
   char description[16];
   int count;
};  // size = 20 bytes

struct large_obj {
    char text[1024][1024];
    double factor[1024][1024];
}; // size = 9 MB

void f1(small_obj arg);  // OK, puts 20 bytes on the stack, f1 gets a copy
                                // of the struct. Any modifications to the struct are
                                // local ot f1

void f2(small_obj* arg);  // stack is 4 bytes only. changes to f2 members will not
                                 // be seen by caller

void f3(const small_obj *arg); // stack is 4 bytes only. attempts within f3 to modify members
                               // should produce compiler warnings

void f4(small_obj& arg);   // similar to f2(), but uses C++ reference type

void f5(const small_obj& arg);   // similar to f3, but uses C++ reference type

void f6(large_obj arg);   // questionable.  This copys 9 MB onto the stack, which might
                          // be more than the OS can handle, and might incur performance
                          // penalties you can avoid by passing as a pointer or reference

Quote:

I can highly recommend learning the whole process on a simple software renderer