320 lines
7.3 KiB
C
320 lines
7.3 KiB
C
/*
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** blendeq.c - Demonstrates the use of the blend_minmax, blend_subtract,
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** and blend_logic_op extensions using glBlendEquationEXT.
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**
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** Over a two-color backround, draw rectangles using twelve blend
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** options. The values are read back as UNSIGNED_BYTE and printed
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** in hex over each value. These values are useful for logic
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** op comparisons when channels are 8 bits deep.
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*/
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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#ifdef _WIN32
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#include <windows.h>
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#endif
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#define GL_GLEXT_PROTOTYPES
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#include <GL/glut.h>
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GLenum doubleBuffer;
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static int dithering = 0;
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int use11ops = 0;
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int supportlogops = 0;
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static int doPrint = 1;
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static int deltaY;
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GLint windW, windH;
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static void DrawString(const char *string)
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{
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int i;
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for (i = 0; string[i]; i++)
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glutBitmapCharacter(GLUT_BITMAP_9_BY_15, string[i]);
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}
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static void Init(void)
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{
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glDisable(GL_DITHER);
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glShadeModel(GL_FLAT);
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}
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static void Reshape(int width, int height)
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{
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windW = (GLint)width;
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windH = (GLint)height;
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glViewport(0, 0, (GLint)width, (GLint)height);
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deltaY = windH /16;
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluOrtho2D(0, windW, 0, windH);
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glMatrixMode(GL_MODELVIEW);
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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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switch (key) {
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case 27:
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exit(1);
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case 'd':
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dithering = !dithering;
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break;
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case 'l':
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if (supportlogops == 3)
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use11ops = (!use11ops);
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if (use11ops)
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printf("Using GL 1.1 color logic ops.\n");
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else printf("Using GL_EXT_blend_logic_op.\n");
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break;
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default:
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return;
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}
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glutPostRedisplay();
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}
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static void PrintColorStrings( void )
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{
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GLubyte ubbuf[3];
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int i, xleft, xright;
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char colorString[18];
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xleft = 5 + windW/4;
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xright = 5 + windW/2;
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for (i = windH - deltaY + 4; i > 0; i-=deltaY) {
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glReadPixels(xleft, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
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sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
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ubbuf[0], ubbuf[1], ubbuf[2]);
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glRasterPos2f(xleft, i);
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DrawString(colorString);
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glReadPixels(xright, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
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sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
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ubbuf[0], ubbuf[1], ubbuf[2]);
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glRasterPos2f(xright, i);
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DrawString(colorString);
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}
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}
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static void Draw(void)
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{
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int stringOffset = 5, stringx = 8;
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int x1, x2, xleft, xright;
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int i;
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(dithering) ? glEnable(GL_DITHER) : glDisable(GL_DITHER);
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glDisable(GL_BLEND);
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if (supportlogops & 2)
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glDisable(GL_COLOR_LOGIC_OP);
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glClearColor(0.5, 0.6, 0.1, 1.0);
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glClear(GL_COLOR_BUFFER_BIT);
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/* Draw background */
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glColor3f(0.1, 0.1, 1.0);
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glRectf(0.0, 0.0, windW/2, windH);
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/* Draw labels */
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glColor3f(0.8, 0.8, 0.0);
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i = windH - deltaY + stringOffset;
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("SOURCE");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("DEST");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("min");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("max");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("subtract");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("reverse_subtract");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("clear");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("set");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("copy");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("noop");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("and");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("invert");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("or");
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glRasterPos2f(stringx, i); i -= deltaY;
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DrawString("xor");
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i = windH - deltaY;
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x1 = windW/4;
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x2 = 3 * windW/4;
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xleft = 5 + windW/4;
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xright = 5 + windW/2;
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/* Draw foreground color for comparison */
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glColor3f(0.9, 0.2, 0.8);
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glRectf(x1, i, x2, i+deltaY);
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/* Leave one rectangle of background color */
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/* Begin test cases */
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glEnable(GL_BLEND);
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glBlendFunc(GL_ONE, GL_ONE);
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i -= 2*deltaY;
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glBlendEquationEXT(GL_MIN_EXT);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glBlendEquationEXT(GL_MAX_EXT);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glBlendEquationEXT(GL_FUNC_SUBTRACT_EXT);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glBlendEquationEXT(GL_FUNC_REVERSE_SUBTRACT_EXT);
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glRectf(x1, i, x2, i+deltaY);
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glBlendFunc(GL_ONE, GL_ZERO);
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i -= deltaY;
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if (!use11ops)
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glBlendEquationEXT(GL_LOGIC_OP);
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else
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glEnable(GL_COLOR_LOGIC_OP);
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glLogicOp(GL_CLEAR);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_SET);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_COPY);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_NOOP);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_AND);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_INVERT);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_OR);
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glRectf(x1, i, x2, i+deltaY);
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i -= deltaY;
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glLogicOp(GL_XOR);
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glRectf(x1, i, x2, i+deltaY);
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glRectf(x1, i+10, x2, i+5);
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if (doPrint) {
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glDisable(GL_BLEND);
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if (supportlogops & 2)
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glDisable(GL_COLOR_LOGIC_OP);
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glColor3f(1.0, 1.0, 1.0);
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PrintColorStrings();
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}
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glFlush();
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if (doubleBuffer) {
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glutSwapBuffers();
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}
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}
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static GLenum Args(int argc, char **argv)
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{
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GLint i;
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doubleBuffer = GL_FALSE;
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for (i = 1; i < argc; i++) {
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if (strcmp(argv[i], "-sb") == 0) {
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doubleBuffer = GL_FALSE;
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} else if (strcmp(argv[i], "-db") == 0) {
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doubleBuffer = GL_TRUE;
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} else {
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printf("%s (Bad option).\n", argv[i]);
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return GL_FALSE;
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}
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}
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return GL_TRUE;
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}
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int main(int argc, char **argv)
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{
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GLenum type;
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char *s;
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char *extName1 = "GL_EXT_blend_logic_op";
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char *extName2 = "GL_EXT_blend_minmax";
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char *extName3 = "GL_EXT_blend_subtract";
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char *version;
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glutInit(&argc, argv);
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if (Args(argc, argv) == GL_FALSE) {
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exit(1);
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}
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glutInitWindowPosition(0, 0); glutInitWindowSize( 800, 400);
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type = GLUT_RGB;
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type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
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glutInitDisplayMode(type);
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if (glutCreateWindow("Blend Equation") == GL_FALSE) {
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exit(1);
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}
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/* Make sure blend_logic_op extension is there. */
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s = (char *) glGetString(GL_EXTENSIONS);
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version = (char*) glGetString(GL_VERSION);
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if (!s)
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exit(1);
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if (strstr(s,extName1)) {
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supportlogops = 1;
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use11ops = 0;
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printf("blend_logic_op extension available.\n");
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}
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if (strncmp(version,"1.1",3)>=0) {
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supportlogops += 2;
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use11ops = 1;
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printf("1.1 color logic ops available.\n");
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}
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if (supportlogops == 0) {
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printf("Blend_logic_op extension and GL 1.1 not present.\n");
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exit(1);
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}
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if (strstr(s,extName2) == 0) {
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printf("Blend_minmax extension is not present.\n");
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exit(1);
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}
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if (strstr(s,extName3) == 0) {
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printf("Blend_subtract extension is not present.\n");
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exit(1);
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}
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Init();
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutDisplayFunc(Draw);
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glutMainLoop();
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return 0;
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}
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