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/*
** blendeq.c - Demonstrates the use of the blend_minmax, blend_subtract,
** and blend_logic_op extensions using glBlendEquationEXT.
**
** Over a two-color backround, draw rectangles using twelve blend
** options. The values are read back as UNSIGNED_BYTE and printed
** in hex over each value. These values are useful for logic
** op comparisons when channels are 8 bits deep.
*/
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include "gltk.h"
GLenum doubleBuffer, directRender;
static int dithering = 0;
static int doPrint = 1;
static int deltaY;
GLint windW, windH;
GLuint bitmapBase;
static void Init(void)
{
bitmapBase = glGenLists(256);
if (tkCreateBitmapFont(bitmapBase) == GL_FALSE) {
tkQuit();
}
glDisable(GL_DITHER);
glShadeModel(GL_FLAT);
}
static void Reshape(int width, int height)
{
windW = (GLint)width;
windH = (GLint)height;
glViewport(0, 0, (GLint)width, (GLint)height);
deltaY = windH /16;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, windW, 0, windH);
glMatrixMode(GL_MODELVIEW);
}
static GLenum Key(int key, GLenum mask)
{
switch (key) {
case TK_ESCAPE:
tkQuit();
case TK_d:
dithering = !dithering;
break;
default:
return GL_FALSE;
}
return GL_TRUE;
}
static void PrintColorStrings( void )
{
GLubyte ubbuf[3], ubcolor[3];
int i, xleft, xright;
char colorString[18];
xleft = 5 + windW/4;
xright = 5 + windW/2;
for (i = windH - deltaY + 4; i > 0; i-=deltaY) {
glReadPixels(xleft, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
ubbuf[0], ubbuf[1], ubbuf[2]);
glRasterPos2f(xleft, i);
tkDrawStr(bitmapBase, colorString);
glReadPixels(xright, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
ubbuf[0], ubbuf[1], ubbuf[2]);
glRasterPos2f(xright, i);
tkDrawStr(bitmapBase, colorString);
}
}
static void Draw(void)
{
float xscale, yscale;
GLfloat x, y;
int i, j;
GLfloat buf[3];
GLubyte ubbuf[3], ubcolor[3];
int stringOffset = 5, stringx = 8;
int x1, x2, xleft, xright;
(dithering) ? glEnable(GL_DITHER) : glDisable(GL_DITHER);
glDisable(GL_BLEND);
glClearColor(0.5, 0.6, 0.1, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
/* Draw background */
glColor3f(0.1, 0.1, 1.0);
glRectf(0.0, 0.0, windW/2, windH);
/* Draw labels */
glColor3f(0.8, 0.8, 0.0);
i = windH - deltaY + stringOffset;
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "SOURCE");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "DEST");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "min");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "max");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "subtract");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "reverse_subtract");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "clear");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "set");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "copy");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "noop");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "and");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "invert");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "or");
glRasterPos2f(stringx, i); i -= deltaY;
tkDrawStr(bitmapBase, "xor");
i = windH - deltaY;
x1 = windW/4;
x2 = 3 * windW/4;
xleft = 5 + windW/4;
xright = 5 + windW/2;
/* Draw foreground color for comparison */
glColor3f(0.9, 0.2, 0.8);
glRectf(x1, i, x2, i+deltaY);
/* Leave one rectangle of background color */
/* Begin test cases */
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE);
i -= 2*deltaY;
glBlendEquationEXT(GL_MIN_EXT);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_MAX_EXT);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_FUNC_SUBTRACT_EXT);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_FUNC_REVERSE_SUBTRACT_EXT);
glRectf(x1, i, x2, i+deltaY);
glBlendFunc(GL_ONE, GL_ZERO);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_CLEAR);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_SET);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_COPY);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_NOOP);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_AND);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_INVERT);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_OR);
glRectf(x1, i, x2, i+deltaY);
i -= deltaY;
glBlendEquationEXT(GL_LOGIC_OP);
glLogicOp(GL_XOR);
glRectf(x1, i, x2, i+deltaY);
glRectf(x1, i+10, x2, i+5);
if (doPrint) {
glDisable(GL_BLEND);
glColor3f(1.0, 1.0, 1.0);
PrintColorStrings();
}
glFlush();
if (doubleBuffer) {
tkSwapBuffers();
}
}
static GLenum Args(int argc, char **argv)
{
GLint i;
doubleBuffer = GL_FALSE;
directRender = GL_TRUE;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-sb") == 0) {
doubleBuffer = GL_FALSE;
} else if (strcmp(argv[i], "-db") == 0) {
doubleBuffer = GL_TRUE;
} else if (strcmp(argv[i], "-dr") == 0) {
directRender = GL_TRUE;
} else if (strcmp(argv[i], "-ir") == 0) {
directRender = GL_FALSE;
} else {
printf("%s (Bad option).\n", argv[i]);
return GL_FALSE;
}
}
return GL_TRUE;
}
void main(int argc, char **argv)
{
GLenum type;
char *s;
char *extName1 = "GL_EXT_blend_logic_op";
char *extName2 = "GL_EXT_blend_minmax";
char *extName3 = "GL_EXT_blend_subtract";
if (Args(argc, argv) == GL_FALSE) {
tkQuit();
}
tkInitPosition(0, 0, 800, 400);
type = TK_RGB;
type |= (doubleBuffer) ? TK_DOUBLE : TK_SINGLE;
type |= (directRender) ? TK_DIRECT : TK_INDIRECT;
tkInitDisplayMode(type);
if (tkInitWindow("Blend Equation") == GL_FALSE) {
tkQuit();
}
/* Make sure blend_logic_op extension is there. */
s = (char *) glGetString(GL_EXTENSIONS);
if (!s)
tkQuit();
if (strstr(s,extName1) == 0) {
printf("Blend_logic_op extension is not present.\n");
tkQuit();
}
if (strstr(s,extName2) == 0) {
printf("Blend_minmax extension is not present.\n");
tkQuit();
}
if (strstr(s,extName3) == 0) {
printf("Blend_subtract extension is not present.\n");
tkQuit();
}
Init();
tkExposeFunc(Reshape);
tkReshapeFunc(Reshape);
tkKeyDownFunc(Key);
tkDisplayFunc(Draw);
tkExec();
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.