blendsquare.c 4.39 KB
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/*
 * (C) Copyright IBM Corporation 2004
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, and/or sell copies of the Software, and to permit persons to whom
 * the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEM, IBM AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * \file blendsquare.c
 * 
 * Simple test of GL_NV_blend_square functionality.  Four squares are drawn
 * with different blending modes, but all should be rendered with the same
 * final color.
 *
 * \author Ian Romanick <idr@us.ibm.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <GL/glew.h>
#include <GL/glut.h>

static int Width = 400;
static int Height = 200;
static const GLfloat Near = 5.0, Far = 25.0;

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static void Display(void)
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{
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	glClearColor(0.2, 0.2, 0.8, 0);
	glClear(GL_COLOR_BUFFER_BIT);

	glPushMatrix();

	glTranslatef(-4.5, 0, 0);
	glBlendFunc(GL_ONE, GL_ZERO);
	glBegin(GL_QUADS);
	glColor3f(0.5 * 0.5, 0.5 * 0.5, 0.5 * 0.5);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();


	glTranslatef(3.0, 0, 0);
	glBlendFunc(GL_ONE, GL_ZERO);
	glBegin(GL_QUADS);
	glColor3f(0.5, 0.5, 0.5);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();

	glBlendFunc(GL_DST_COLOR, GL_ZERO);
	glBegin(GL_QUADS);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();


	glTranslatef(3.0, 0, 0);
	glBlendFunc(GL_SRC_COLOR, GL_ZERO);
	glBegin(GL_QUADS);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();


	glTranslatef(3.0, 0, 0);
	glBlendFunc(GL_ONE, GL_ZERO);
	glBegin(GL_QUADS);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();

	glBlendFunc(GL_ZERO, GL_DST_COLOR);
	glBegin(GL_QUADS);
	glVertex2f(-1, -1);
	glVertex2f( 1, -1);
	glVertex2f( 1,  1);
	glVertex2f(-1,  1);
	glEnd();

	glPopMatrix();

	glutSwapBuffers();
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}


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static void Reshape(int width, int height)
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{
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	GLfloat ar = (float) width / (float) height;
	Width = width;
	Height = height;
	glViewport(0, 0, width, height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustum(-ar, ar, -1.0, 1.0, Near, Far);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	glTranslatef(0.0, 0.0, -15.0);
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}


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static void Key(unsigned char key, int x, int y)
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{
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	(void) x;
	(void) y;
	switch (key) {
	case 27:
		exit(0);
		break;
	}
	glutPostRedisplay();
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}


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static void Init(void)
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{
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	const char * const ver_string = (const char *)
		glGetString(GL_VERSION);
	const double version = strtod(ver_string, NULL);

	printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
	printf("GL_VERSION = %s\n", ver_string);

	if ((version < 1.4) && !glutExtensionSupported("GL_NV_blend_square")) {
		printf("Sorry, this program requires either OpenGL 1.4 or GL_NV_blend_square\n");
		exit(1);
	}

	printf("\nAll 4 squares should be the same color.  The two on the left are drawn\n"
	       "without NV_blend_square functionality, and the two on the right are drawn\n"
	       "with NV_blend_square functionality.  If the two on the left are dark, but\n"
	       "the two on the right are not, then NV_blend_square is broken.\n");
	glEnable(GL_BLEND);
	glBlendEquation(GL_FUNC_ADD);
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}


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int main(int argc, char *argv[])
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{
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	glutInit(&argc, argv);
	glutInitWindowPosition(0, 0);
	glutInitWindowSize(Width, Height);
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
	glutCreateWindow("GL_NV_blend_square test");
	glewInit();
	glutReshapeFunc(Reshape);
	glutKeyboardFunc(Key);
	glutDisplayFunc(Display);
	Init();
	glutMainLoop();
	return 0;
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}