path: root/tests/glean/tstencil2.cpp

// BEGIN_COPYRIGHT -*- glean -*-
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// Test two-sided stencil extensions
// Brian Paul
// 19 Feb 2009


// This test could be better:
// 1. Generate random state vectors, render and compare to expected values
// 2. Exercise separate front/back reference values and masks for the
//    EXT and GL2 variations.



#include <cassert>
#include <cstring>
#include "tstencil2.h"


namespace GLEAN {

// ATI
static PFNGLSTENCILOPSEPARATEATIPROC glStencilOpSeparateATI_func;
static PFNGLSTENCILFUNCSEPARATEATIPROC glStencilFuncSeparateATI_func;

// EXT
static PFNGLACTIVESTENCILFACEEXTPROC glActiveStencilFaceEXT_func;

// GL2
static PFNGLSTENCILOPSEPARATEPROC glStencilOpSeparate_func;
static PFNGLSTENCILFUNCSEPARATEPROC glStencilFuncSeparate_func;
static PFNGLSTENCILMASKSEPARATEPROC glStencilMaskSeparate_func;


// two-sided methods:
#define ATI 1
#define EXT 2
#define GL2 3


Stencil2Result::Stencil2Result()
{
	pass = false;
}


void
Stencil2Test::get_ext_functions(void)
{
	// ATI
	glStencilOpSeparateATI_func = (PFNGLSTENCILOPSEPARATEATIPROC)
		GLUtils::getProcAddress("glStencilOpSeparateATI");
	glStencilFuncSeparateATI_func = (PFNGLSTENCILFUNCSEPARATEATIPROC)
		GLUtils::getProcAddress("glStencilFuncSeparateATI");

	// EXT
	glActiveStencilFaceEXT_func = (PFNGLACTIVESTENCILFACEEXTPROC)
		GLUtils::getProcAddress("glActiveStencilFaceEXT");

	// GL2
	glStencilOpSeparate_func = (PFNGLSTENCILOPSEPARATEPROC)
		GLUtils::getProcAddress("glStencilOpSeparate");

	glStencilFuncSeparate_func = (PFNGLSTENCILFUNCSEPARATEPROC)
		GLUtils::getProcAddress("glStencilFuncSeparate");

	glStencilMaskSeparate_func= (PFNGLSTENCILMASKSEPARATEPROC)
		GLUtils::getProcAddress("glStencilMaskSeparate");
}


bool
Stencil2Test::have_ATI_separate_stencil(void) const
{
	return GLUtils::haveExtension("GL_ATI_separate_stencil");
}

bool
Stencil2Test::have_EXT_stencil_two_side(void) const
{
	return GLUtils::haveExtension("GL_EXT_stencil_two_side");
}

bool
Stencil2Test::have_GL2_stencil_two_side(void) const
{
	return GLUtils::getVersion() >= 2.0;
}

bool
Stencil2Test::have_stencil_wrap(void) const
{
	if (GLUtils::getVersion() >= 2.0) {
		return true;
	}
	else if (GLUtils::haveExtension("GL_EXT_stencil_wrap")) {
		return true;
	}
	return false;
}


// Draw four quads:
//   Bottom row uses GL_CCW
//   Top row uses GL_CW
//   Left column is front-facing
//   Right column is back-facing
// Check the values in the stencil buffer to see if they match
// the expected values.
bool
Stencil2Test::render_test(GLuint expectedFront, GLuint expectedBack)
{
	GLint x0 = 0;
	GLint x1 = windowSize / 2;
	GLint x2 = windowSize;
	GLint y0 = 0;
	GLint y1 = windowSize / 2;
	GLint y2 = windowSize;

	glFrontFace(GL_CCW); // this the GL default

	// lower left quad = front-facing
	glBegin(GL_TRIANGLE_FAN);
	glVertex2f(x0, y0);
	glVertex2f(x1, y0);
	glVertex2f(x1, y1);
	glVertex2f(x0, y1);
	glEnd();

	// lower right quad = back-facing
	glBegin(GL_TRIANGLE_FAN);
	glVertex2f(x1, y0);
	glVertex2f(x1, y1);
	glVertex2f(x2, y1);
	glVertex2f(x2, y0);
	glEnd();

	glFrontFace(GL_CW);

	// upper left quad = front-facing
	glBegin(GL_TRIANGLE_FAN);
	glVertex2f(x0, y1);
	glVertex2f(x0, y2);
	glVertex2f(x1, y2);
	glVertex2f(x1, y1);
	glEnd();

	// upper right quad = back-facing
	glBegin(GL_TRIANGLE_FAN);
	glVertex2f(x1, y1);
	glVertex2f(x2, y1);
	glVertex2f(x2, y2);
	glVertex2f(x1, y2);
	glEnd();
	
	GLint midXleft = (x0 + x1) / 2;
	GLint midXright = (x1 + x2) / 2;
	GLint midYlower = (y0 + y1) / 2;
	GLint midYupper = (y1 + y2) / 2;
	GLuint lowerLeftVal, lowerRightVal;
	GLuint upperLeftVal, upperRightVal;

	glReadPixels(midXleft, midYlower, 1, 1,
		     GL_STENCIL_INDEX, GL_UNSIGNED_INT, &lowerLeftVal);
	glReadPixels(midXright, midYlower, 1, 1,
		     GL_STENCIL_INDEX, GL_UNSIGNED_INT, &lowerRightVal);

	glReadPixels(midXleft, midYupper, 1, 1,
		     GL_STENCIL_INDEX, GL_UNSIGNED_INT, &upperLeftVal);
	glReadPixels(midXright, midYupper, 1, 1,
		     GL_STENCIL_INDEX, GL_UNSIGNED_INT, &upperRightVal);

	if (lowerLeftVal != upperLeftVal) {
		env->log << "FAIL:\n";
		env->log << "\tLower-left value (" << lowerLeftVal
			 << ") doesn't match upper-left value ("
			 << upperLeftVal
			 << ").\n";
		env->log << "\tLooks like a front/back-face orientation bug.\n";
		return false;
	}

	if (lowerRightVal != upperRightVal) {
		env->log << "FAIL:\n";
		env->log << "\tLower-right value (" << lowerRightVal
			 << ") doesn't match upper-right value ("
			 << upperRightVal
			 << ").\n";
		env->log << "\tLooks like a front/back-face orientation bug.\n";
		return false;
	}


	if (lowerLeftVal != expectedFront) {
		env->log << "FAIL:\n";
		env->log << "\tExpected front-face stencil value is "
			 << expectedFront
			 << " but found " << lowerLeftVal << "\n";
		return false;
	}
	else if (lowerRightVal != expectedBack) {
		env->log << "FAIL:\n";
		env->log << "\tExpected back-face stencil value is " << expectedBack
			 << " but found " << lowerRightVal << "\n";
		return false;
	}
	else {
		return true;
	}
}


bool
Stencil2Test::compare_state(int method, GLenum found, GLenum expected,
			    const char *msg)
{
	if (found != expected) {
		env->log << "FAIL:\n";
		env->log << "\tQuery of " << msg << " state failed for ";
		switch (method) {
		case ATI:
			env->log << "GL_ATI_separate_stencil";
			break;
		case EXT:
			env->log << "GL_EXT_stencil_two_side";
			break;
		case GL2:
			env->log << "GL 2.x two-sided stencil";
			break;
		default:
			assert(0);
		}
		env->log << "\n";
		char s[1000];
		sprintf(s, "\tFound 0x%x, expected 0x%x\n", found, expected);
		env->log << s;
		return false;
	}
	return true;
}


// Set stencil state, plus read it back and check that it's correct.
// Note: we only test with one reference value and one mask value
// even though EXT and GL2 support separate front/back refs/masks
bool
Stencil2Test::set_stencil_state(int method,
				GLenum frontStencilFail,
				GLenum backStencilFail,
				GLenum frontZFail,
				GLenum backZFail,
				GLenum frontZPass,
				GLenum backZPass,
				GLenum frontFunc,
				GLenum backFunc,
				GLint frontRef,
				GLint backRef,
				GLuint frontMask,
				GLuint backMask,
				GLuint frontWriteMask,
				GLuint backWriteMask)
{
	GLint get_frontStencilFail;
	GLint get_backStencilFail;
	GLint get_frontZFail;
	GLint get_backZFail;
	GLint get_frontZPass;
	GLint get_backZPass;
	GLint get_frontFunc;
	GLint get_backFunc;
	GLint get_frontRef;
	GLint get_backRef;
	GLint get_frontMask;
	GLint get_backMask;
	GLint get_frontWriteMask;
	GLint get_backWriteMask;
	GLint twoEnabled;

	switch (method) {
	case ATI:
		assert(frontRef == backRef);
		assert(frontMask == backMask);
		assert(frontWriteMask == backWriteMask);

		// set state
		glStencilOpSeparateATI_func(GL_FRONT,
					    frontStencilFail,
					    frontZFail,
					    frontZPass);

		glStencilOpSeparateATI_func(GL_BACK,
					    backStencilFail,
					    backZFail,
					    backZPass);

		glStencilFuncSeparateATI_func(frontFunc, backFunc, frontRef, frontMask);

		glStencilMask(frontWriteMask);

		// get state
		glGetIntegerv(GL_STENCIL_FAIL, &get_frontStencilFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &get_frontZFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &get_frontZPass);
		glGetIntegerv(GL_STENCIL_FUNC, &get_frontFunc);
		glGetIntegerv(GL_STENCIL_REF, &get_frontRef);
		glGetIntegerv(GL_STENCIL_VALUE_MASK, &get_frontMask);
		glGetIntegerv(GL_STENCIL_WRITEMASK, &get_frontWriteMask);

		glGetIntegerv(GL_STENCIL_BACK_FUNC_ATI, &get_backFunc);
		glGetIntegerv(GL_STENCIL_BACK_FAIL_ATI, &get_backStencilFail);
		glGetIntegerv(GL_STENCIL_BACK_PASS_DEPTH_FAIL_ATI, &get_backZFail);
		glGetIntegerv(GL_STENCIL_BACK_PASS_DEPTH_PASS_ATI, &get_backZPass);
		get_backRef = get_frontRef;
		get_backMask = get_frontMask;
		get_backWriteMask = get_frontWriteMask;
		twoEnabled = GL_TRUE;
		break;

	case EXT:
		// set state
		glEnable(GL_STENCIL_TEST_TWO_SIDE_EXT);

		glActiveStencilFaceEXT_func(GL_FRONT);
		glStencilOp(frontStencilFail, frontZFail, frontZPass);
		glStencilFunc(frontFunc, frontRef, frontMask);
		glStencilMask(frontWriteMask);

		glActiveStencilFaceEXT_func(GL_BACK);
		glStencilOp(backStencilFail, backZFail, backZPass);
		glStencilFunc(backFunc, backRef, backMask);
		glStencilMask(backWriteMask);

		// get state
		glActiveStencilFaceEXT_func(GL_FRONT);
		glGetIntegerv(GL_STENCIL_FAIL, &get_frontStencilFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &get_frontZFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &get_frontZPass);
		glGetIntegerv(GL_STENCIL_FUNC, &get_frontFunc);
		glGetIntegerv(GL_STENCIL_REF, &get_frontRef);
		glGetIntegerv(GL_STENCIL_VALUE_MASK, &get_frontMask);
		glGetIntegerv(GL_STENCIL_WRITEMASK, &get_frontWriteMask);
		glActiveStencilFaceEXT_func(GL_BACK);
		glGetIntegerv(GL_STENCIL_FAIL, &get_backStencilFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &get_backZFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &get_backZPass);
		glGetIntegerv(GL_STENCIL_FUNC, &get_backFunc);
		glGetIntegerv(GL_STENCIL_REF, &get_backRef);
		glGetIntegerv(GL_STENCIL_VALUE_MASK, &get_backMask);
		glGetIntegerv(GL_STENCIL_WRITEMASK, &get_backWriteMask);
		glGetIntegerv(GL_STENCIL_TEST_TWO_SIDE_EXT, &twoEnabled);
		break;

	case GL2:
		// set state
		glStencilOpSeparate_func(GL_FRONT,
					 frontStencilFail,
					 frontZFail,
					 frontZPass);
		glStencilOpSeparate_func(GL_BACK,
					 backStencilFail,
					 backZFail,
					 backZPass);
		glStencilFuncSeparate_func(GL_FRONT, frontFunc, frontRef, frontMask);
		glStencilFuncSeparate_func(GL_BACK, backFunc, backRef, backMask);
		glStencilMaskSeparate_func(GL_FRONT, frontWriteMask);
		glStencilMaskSeparate_func(GL_BACK, backWriteMask);

		// get state
		glGetIntegerv(GL_STENCIL_FAIL, &get_frontStencilFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &get_frontZFail);
		glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &get_frontZPass);
		glGetIntegerv(GL_STENCIL_FUNC, &get_frontFunc);
		glGetIntegerv(GL_STENCIL_REF, &get_frontRef);
		glGetIntegerv(GL_STENCIL_VALUE_MASK, &get_frontMask);
		glGetIntegerv(GL_STENCIL_WRITEMASK, &get_frontWriteMask);

		glGetIntegerv(GL_STENCIL_BACK_FUNC, &get_backFunc);
		glGetIntegerv(GL_STENCIL_BACK_FAIL, &get_backStencilFail);
		glGetIntegerv(GL_STENCIL_BACK_PASS_DEPTH_FAIL, &get_backZFail);
		glGetIntegerv(GL_STENCIL_BACK_PASS_DEPTH_PASS, &get_backZPass);
		glGetIntegerv(GL_STENCIL_BACK_REF, &get_backRef);
		glGetIntegerv(GL_STENCIL_BACK_VALUE_MASK, &get_backMask);
		glGetIntegerv(GL_STENCIL_BACK_WRITEMASK, &get_backWriteMask);
		twoEnabled = GL_TRUE;
		break;

	default:
		assert(0);
	}

	// mask off bits we don't care about
	get_frontMask &= stencilMax;
	frontMask &= stencilMax;
	get_backMask &= stencilMax;
	backMask &= stencilMax;
	get_frontWriteMask &= stencilMax;
	frontWriteMask &= stencilMax;
	get_backWriteMask &= stencilMax;
	backWriteMask &= stencilMax;

	GLenum err = glGetError();
	if (err != GL_NO_ERROR) {
		env->log << "FAIL:\n";
		env->log << "\tGL error " << err << " detected.\n";
		return false;
	}

	// see if state-get matches state-set

	if (!compare_state(method, get_frontStencilFail, frontStencilFail,
			  "front stencil fail"))
		return false;

	if (!compare_state(method, get_backStencilFail, backStencilFail,
			   "back stencil fail"))
		return false;

	if (!compare_state(method, get_frontZFail, frontZFail,
			   "front Z fail"))
		return false;

	if (!compare_state(method, get_backZFail, backZFail,
			   "back Z fail"))
		return false;

	if (!compare_state(method, get_frontZPass, frontZPass,
			   "front Z pass"))
		return false;

	if (!compare_state(method, get_backZPass, backZPass,
			   "back Z pass"))
		return false;

	if (!compare_state(method, get_frontFunc, frontFunc,
			   "front stencil func"))
		return false;

	if (!compare_state(method, get_backFunc, backFunc,
			   "back stencil func"))
		return false;

	if (!compare_state(method, get_frontRef, frontRef,
		           "front stencil ref"))
		return false;

	if (!compare_state(method, get_backRef, backRef,
		           "back stencil ref"))
		return false;

	if (!compare_state(method, get_frontMask, frontMask,
		           "front stencil mask"))
		return false;

	if (!compare_state(method, get_backMask, backMask,
		           "back stencil mask"))
		return false;

	if (!compare_state(method, get_frontWriteMask, frontWriteMask,
		           "front stencil writemask"))
		return false;

	if (!compare_state(method, get_backWriteMask, backWriteMask,
		           "back stencil writemask"))
		return false;

	if (!compare_state(method, twoEnabled, GL_TRUE, "two-side enable"))
		return false;

	return true;
}


bool
Stencil2Test::set_stencil_state(int method,
				GLenum frontStencilFail,
				GLenum backStencilFail,
				GLenum frontZFail,
				GLenum backZFail,
				GLenum frontZPass,
				GLenum backZPass,
				GLenum frontFunc,
				GLenum backFunc,
				GLint ref,
				GLuint mask,
				GLuint writeMask)
{
	return set_stencil_state(method,
				 frontStencilFail,
				 backStencilFail,
				 frontZFail,
				 backZFail,
				 frontZPass,
				 backZPass,
				 frontFunc,
				 backFunc,
				 ref, // frontRef
				 ref, // backRef
				 mask, // frontMask
				 mask, // backMask
				 writeMask, // frontWriteMask
				 writeMask); // backWriteMask
}


void
Stencil2Test::reset_stencil_state(int method)
{
	switch (method) {
	case ATI:
		break;
	case EXT:
		glDisable(GL_STENCIL_TEST_TWO_SIDE_EXT);
		glActiveStencilFaceEXT_func(GL_FRONT);
		break;
	case GL2:
		break;
	default:
		assert(0);
	}
}


bool
Stencil2Test::test_stencil(int method)
{
	bool pass;

	glEnable(GL_STENCIL_TEST);

	//============================================================
	// No depth testing
	glDisable(GL_DEPTH_TEST);

	glClear(GL_COLOR_BUFFER_BIT |
		GL_STENCIL_BUFFER_BIT |
		GL_DEPTH_BUFFER_BIT);


	// set stencil buffer vals to 5
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_REPLACE, GL_REPLACE,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 5, ~0);  // ref, mask
	if (pass)
		pass = render_test(5, 5);
	reset_stencil_state(method);
	if (!pass)
		return false;

	// incr front val to 6, decr back val to 4
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_INCR, GL_DECR,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 5, ~0);  // ref, mask
	if (pass)
		pass = render_test(6, 4);
	reset_stencil_state(method);
	if (!pass)
		return false;

	// if front==6, keep
	// if back<6, replace with zero
	// final: front=6, back=0
	pass = set_stencil_state(method,
				 GL_KEEP, GL_ZERO,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_KEEP, GL_KEEP,  // z pass
				 GL_EQUAL, GL_LESS,  // stencil func
				 6, ~0);  // ref, mask
	if (pass)
		pass = render_test(6, 0);
	reset_stencil_state(method);
	if (!pass)
		return false;

	// if front!=10, keep, else decr
	// if back<10, keep, else incr
	// final: front=6, back=1
	pass = set_stencil_state(method,
				 GL_DECR, GL_INCR,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_KEEP, GL_KEEP,  // z pass
				 GL_NOTEQUAL, GL_LESS,  // stencil func
				 10, ~0);  // ref, mask
	if (pass)
		pass = render_test(6, 1);
	reset_stencil_state(method);
	if (!pass)
		return false;

	if (method != ATI) {
		// if front!=10, keep, else decr
		// if back<10, keep, else incr
		// final: front=6, back=1
		pass = set_stencil_state(method,
					 GL_DECR, GL_INCR,  // stencil fail
					 GL_KEEP, GL_KEEP,  // z fail
					 GL_REPLACE, GL_REPLACE,  // z pass
					 GL_ALWAYS, GL_ALWAYS,  // stencil func
					 0xf6, 0xf1, // ref
					 0xff, 0xff, // mask
					 0x60, 0x10); // writeMask
		if (pass)
			pass = render_test(0x66, 0x11);
		reset_stencil_state(method);
		if (!pass)
			return false;
	}

	// reset write mask for clear
	set_stencil_state(method,
			  GL_KEEP, GL_KEEP,  // stencil fail
			  GL_KEEP, GL_KEEP,  // z fail
			  GL_REPLACE, GL_REPLACE,  // z pass
			  GL_ALWAYS, GL_ALWAYS,  // stencil func
			  0, 0,
			  ~0, ~0,
			  ~0, ~0);

	//============================================================
	// Now begin tests with depth test
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);

	glClear(GL_COLOR_BUFFER_BIT |
		GL_STENCIL_BUFFER_BIT |
		GL_DEPTH_BUFFER_BIT);

	// set stencil buffer vals to 7, set Z values
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_REPLACE, GL_REPLACE,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 7, ~0);  // ref, mask
	if (pass)
		pass = render_test(7, 7);
	reset_stencil_state(method);
	if (!pass)
		return false;


	// GL_LESS test should fail everywhere
	// decr front to 5, incr back to 2
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_DECR, GL_INCR,  // z fail
				 GL_KEEP, GL_KEEP,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 99, ~0);  // ref, mask
	if (pass)
		pass = render_test(6, 8);
	reset_stencil_state(method);
	if (!pass)
		return false;


	// set depth test = GL_EQUAL
	// Z test should pass everywhere
	// set front to 3
	// decr back to 7
	glDepthFunc(GL_EQUAL);
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_REPLACE, GL_DECR,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 3, ~0);  // ref, mask
	if (pass)
		pass = render_test(3, 7);
	reset_stencil_state(method);
	if (!pass)
		return false;


	// incr front to 4 (by z pass), decr back to 6 (by stencil fail)
	pass = set_stencil_state(method,
				 GL_DECR, GL_INCR,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_INCR, GL_DECR,  // z pass
				 GL_EQUAL, GL_NOTEQUAL,  // stencil func
				 3, ~0);  // ref, mask
	if (pass)
		pass = render_test(4, 6);
	reset_stencil_state(method);
	if (!pass)
		return false;


	//============================================================
	// Disable depth test
	glDisable(GL_DEPTH_TEST);

	// test stencil value mask
	// only test bit 1 in stencil values
	// if !(front&0x2 == 15&0x2), decr to 3 (should happen)
	// if !(back&0x2 == 15&0x2), incr to 7 (should not happen)
	pass = set_stencil_state(method,
				 GL_DECR, GL_INCR,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_KEEP, GL_KEEP,  // z pass
				 GL_EQUAL, GL_EQUAL,  // stencil func
				 15, 0x2);  // ref, mask
	if (pass)
		pass = render_test(3, 6);
	reset_stencil_state(method);
	if (!pass)
		return false;


	//============================================================
	// Test common two-sided stencil modes for shadow volume rendering
	// Requires stencil +/- wrap feature.

	if (!have_stencil_wrap())
		return true;

	glClear(GL_COLOR_BUFFER_BIT |
		GL_STENCIL_BUFFER_BIT |
		GL_DEPTH_BUFFER_BIT);

	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);

	// "traditional / Z-pass" method:
	// front face: incr on zpass
	// back face: decr on zpass
	// both front and back Z-test should pass here
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_KEEP, GL_KEEP,  // z fail
				 GL_INCR_WRAP_EXT, GL_DECR_WRAP_EXT,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 0, ~0);  // ref, mask
	if (pass)
		pass = render_test(1, stencilMax);
	reset_stencil_state(method);
	if (!pass)
		return false;


	// "Z-fail" method:
	// front face: decr on zfail
	// back face: incr on zfail
	// both front and back Z-test should fail here
	pass = set_stencil_state(method,
				 GL_KEEP, GL_KEEP,  // stencil fail
				 GL_DECR_WRAP_EXT, GL_INCR_WRAP_EXT,  // z fail
				 GL_KEEP, GL_KEEP,  // z pass
				 GL_ALWAYS, GL_ALWAYS,  // stencil func
				 0, ~0);  // ref, mask
	if (pass)
		pass = render_test(0, 0);
	reset_stencil_state(method);
	if (!pass)
		return false;


	return true;
}


void
Stencil2Test::runOne(Stencil2Result &r, Window &w)
{
	(void) w;  // silence warning
	r.pass = true;

	get_ext_functions();

	// how many stencil bits (we assume at least 8 above)
	glGetIntegerv(GL_STENCIL_BITS, &stencilBits);
	stencilMax = (1 << stencilBits) - 1;
	assert(stencilBits >= 8);

	glViewport(0, 0, windowSize, windowSize);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(0, windowSize, 0, windowSize, -1, 1);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	if (have_ATI_separate_stencil()) {
		r.pass &= test_stencil(ATI);
	}

	if (have_EXT_stencil_two_side()) {
		r.pass &= test_stencil(EXT);
	}

	if (have_GL2_stencil_two_side()) {
		r.pass &= test_stencil(GL2);
	}
}


void
Stencil2Test::logOne(Stencil2Result &r)
{
	logPassFail(r);
	logConcise(r);
}


void
Stencil2Result::putresults(ostream &s) const
{
	if (pass) {
		s << "PASS\n";
	}
	else {
		s << "FAIL\n";
	}
}


bool
Stencil2Result::getresults(istream &s)
{
	char result[1000];
	s >> result;

	if (strcmp(result, "FAIL") == 0) {
		pass = false;
	}
	else {
		pass = true;
	}
	return s.good();
}


bool
Stencil2Test::isApplicable() const
{
	return (have_ATI_separate_stencil() ||
		have_EXT_stencil_two_side() ||
		have_EXT_stencil_two_side());
}



// The test object itself:
Stencil2Test stencil2Test("stencil2",
			  "window, rgb, s, z",  // we need stencil and Z
			  "",  // no extension filter, but see isApplicable()
			  "Test two-sided stencil features\n");



} // namespace GLEAN