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authorBrian Paul <brian.paul@tungstengraphics.com>2008-11-21 10:03:19 -0700
committerBrian Paul <brian.paul@tungstengraphics.com>2008-11-21 10:04:37 -0700
commitc45c5c4ca42c29ab73e89449a41a843c24fbe159 (patch)
treea8dd0ad0eb7783be0daa92d116b4d6bc53c31961 /progs
parent3e0164aabb48a99fce58964cad99fd3978ee84f6 (diff)
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added progs/demos/fragcoord.c - tests gl_FragCoord attribute in fragment shader
Fragment's red/greenb/blue is a function gl_FragCoord.xyz
Diffstat (limited to 'progs')
-rw-r--r--progs/glsl/Makefile8
-rw-r--r--progs/glsl/fragcoord.c185
2 files changed, 193 insertions, 0 deletions
diff --git a/progs/glsl/Makefile b/progs/glsl/Makefile
index 41d5849..7c3e750 100644
--- a/progs/glsl/Makefile
+++ b/progs/glsl/Makefile
@@ -15,6 +15,7 @@ PROGS = \
bump \
convolutions \
deriv \
+ fragcoord \
mandelbrot \
multitex \
noise \
@@ -106,6 +107,13 @@ deriv: deriv.o shaderutil.o
$(CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) deriv.o shaderutil.o $(LIBS) -o $@
+fragcoord.o: fragcoord.c extfuncs.h shaderutil.h
+ $(CC) -c -I$(INCDIR) $(CFLAGS) fragcoord.c
+
+fragcoord: fragcoord.o shaderutil.o
+ $(CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) fragcoord.o shaderutil.o $(LIBS) -o $@
+
+
mandelbrot.o: mandelbrot.c extfuncs.h shaderutil.h
$(CC) -c -I$(INCDIR) $(CFLAGS) mandelbrot.c
diff --git a/progs/glsl/fragcoord.c b/progs/glsl/fragcoord.c
new file mode 100644
index 0000000..0b7561f
--- /dev/null
+++ b/progs/glsl/fragcoord.c
@@ -0,0 +1,185 @@
+/**
+ * Test GLSL gl_FragCoord fragment program attribute.
+ * Color the quad's fragments according to their window position.
+ *
+ * Brian Paul
+ * 20 Nov 2008
+ */
+
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/gl.h>
+#include <GL/glut.h>
+#include <GL/glext.h>
+#include "extfuncs.h"
+#include "shaderutil.h"
+
+
+static GLint WinWidth = 200, WinHeight = 200;
+static char *FragProgFile = NULL;
+static char *VertProgFile = NULL;
+static GLuint fragShader;
+static GLuint vertShader;
+static GLuint program;
+static GLint win = 0;
+static GLboolean Anim = GL_TRUE;
+static GLfloat PosX = 0.0, PosY = 0.0;
+
+
+static void
+Idle(void)
+{
+ float r = (WinWidth < WinHeight) ? WinWidth : WinHeight;
+ float a = glutGet(GLUT_ELAPSED_TIME) * 0.001;
+ r *= 0.25;
+ PosX = WinWidth / 2 + r * cos(a);
+ PosY = WinHeight / 2 + r * sin(a);
+
+ glutPostRedisplay();
+}
+
+
+static void
+Redisplay(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT);
+
+ glPushMatrix();
+ glTranslatef(PosX, PosY, 0.0);
+#if 0
+ glBegin(GL_POLYGON);
+ glVertex2f(-50, -50);
+ glVertex2f( 50, -50);
+ glVertex2f( 50, 50);
+ glVertex2f(-50, 50);
+ glEnd();
+#else
+ glutSolidSphere(50, 20, 10);
+#endif
+ glPopMatrix();
+
+ glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+ glViewport(0, 0, width, height);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glOrtho(0, width, 0, height, -55, 55);
+
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+
+ WinWidth = width;
+ WinHeight = height;
+}
+
+
+static void
+CleanUp(void)
+{
+ glDeleteShader_func(fragShader);
+ glDeleteShader_func(vertShader);
+ glDeleteProgram_func(program);
+ glutDestroyWindow(win);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+ (void) x;
+ (void) y;
+
+ switch(key) {
+ case ' ':
+ case 'a':
+ Anim = !Anim;
+ glutIdleFunc(Anim ? Idle : NULL);
+ break;
+ case 27:
+ CleanUp();
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void
+Init(void)
+{
+ static const char *fragShaderText =
+ "void main() { \n"
+ " vec4 scale = vec4(.005, 0.005, 0.5, 1.0);\n"
+ " gl_FragColor = gl_FragCoord * scale; \n"
+ "}\n";
+ static const char *vertShaderText =
+ "void main() {\n"
+ " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
+ "}\n";
+
+ if (!ShadersSupported())
+ exit(1);
+
+ GetExtensionFuncs();
+
+ vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
+ fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
+ program = LinkShaders(vertShader, fragShader);
+
+ glUseProgram_func(program);
+
+ /*assert(glGetError() == 0);*/
+
+ glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
+
+ printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
+
+ assert(glIsProgram_func(program));
+ assert(glIsShader_func(fragShader));
+ assert(glIsShader_func(vertShader));
+
+ glColor3f(1, 0, 0);
+}
+
+
+static void
+ParseOptions(int argc, char *argv[])
+{
+ int i;
+ for (i = 1; i < argc; i++) {
+ if (strcmp(argv[i], "-fs") == 0) {
+ FragProgFile = argv[i+1];
+ }
+ else if (strcmp(argv[i], "-vs") == 0) {
+ VertProgFile = argv[i+1];
+ }
+ }
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitWindowPosition( 0, 0);
+ glutInitWindowSize(WinWidth, WinHeight);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
+ win = glutCreateWindow(argv[0]);
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Redisplay);
+ ParseOptions(argc, argv);
+ Init();
+ glutIdleFunc(Anim ? Idle : NULL);
+ glutMainLoop();
+ return 0;
+}