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-rw-r--r--progs/samples/blendeq.c295
1 files changed, 295 insertions, 0 deletions
diff --git a/progs/samples/blendeq.c b/progs/samples/blendeq.c
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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 <stdlib.h>
+#include <stdio.h>
+#include <GL/glut.h>
+
+
+GLenum doubleBuffer;
+static int dithering = 0;
+static int doPrint = 1;
+static int deltaY;
+GLint windW, windH;
+
+static void DrawString(const char *string)
+{
+ int i;
+
+ for (i = 0; string[i]; i++)
+ glutBitmapCharacter(GLUT_BITMAP_9_BY_15, string[i]);
+}
+
+static void Init(void)
+{
+
+ 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 void Key(unsigned char key, int x, int y)
+{
+
+ switch (key) {
+ case 27:
+ exit(1);
+ case 'd':
+ dithering = !dithering;
+ break;
+ default:
+ return;
+ }
+
+ glutPostRedisplay();
+}
+
+static void PrintColorStrings( void )
+{
+ GLubyte ubbuf[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);
+ DrawString(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);
+ DrawString(colorString);
+ }
+}
+
+static void Draw(void)
+{
+ int stringOffset = 5, stringx = 8;
+ int x1, x2, xleft, xright;
+ int i;
+
+ (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;
+ DrawString("SOURCE");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("DEST");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("min");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("max");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("subtract");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("reverse_subtract");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("clear");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("set");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("copy");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("noop");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("and");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("invert");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("or");
+ glRasterPos2f(stringx, i); i -= deltaY;
+ DrawString("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) {
+ glutSwapBuffers();
+ }
+
+}
+
+static GLenum Args(int argc, char **argv)
+{
+ GLint i;
+
+ doubleBuffer = GL_FALSE;
+
+ 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 {
+ printf("%s (Bad option).\n", argv[i]);
+ return GL_FALSE;
+ }
+ }
+ return GL_TRUE;
+}
+
+int 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";
+
+ glutInit(&argc, argv);
+
+ if (Args(argc, argv) == GL_FALSE) {
+ exit(1);
+ }
+
+ glutInitWindowPosition(0, 0); glutInitWindowSize( 800, 400);
+
+ type = GLUT_RGB;
+ type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
+ glutInitDisplayMode(type);
+
+ if (glutCreateWindow("Blend Equation") == GL_FALSE) {
+ exit(1);
+ }
+
+ /* Make sure blend_logic_op extension is there. */
+ s = (char *) glGetString(GL_EXTENSIONS);
+ if (!s)
+ exit(1);
+ if (strstr(s,extName1) == 0) {
+ printf("Blend_logic_op extension is not present.\n");
+ exit(1);
+ }
+ if (strstr(s,extName2) == 0) {
+ printf("Blend_minmax extension is not present.\n");
+ exit(1);
+ }
+ if (strstr(s,extName3) == 0) {
+ printf("Blend_subtract extension is not present.\n");
+ exit(1);
+ }
+
+ Init();
+
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Draw);
+ glutMainLoop();
+ return 0;
+}
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