demos: add test of vertex-only and fragment-only shader programs

progs/glsl/Makefile

@@ -28,6 +28,7 @@ PROGS = \
 	toyball \
 	twoside \
 	trirast \
+	vert-or-frag-only \
 	vert-tex
 
 
@@ -193,6 +194,14 @@ trirast: trirast.o shaderutil.o
 	$(CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) trirast.o shaderutil.o $(LIBS) -o $@
 
 
+vert-or-frag-only.o: vert-or-frag-only.c extfuncs.h shaderutil.h
+	$(CC) -c -I$(INCDIR) $(CFLAGS) vert-or-frag-only.c
+
+vert-or-frag-only: vert-or-frag-only.o shaderutil.o
+	$(CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) vert-or-frag-only.o shaderutil.o $(LIBS) -o $@
+
+
+
 vert-tex.o: vert-tex.c extfuncs.h shaderutil.h
 	$(CC) -c -I$(INCDIR) $(CFLAGS) vert-tex.c
 

progs/glsl/vert-or-frag-only.c

@@ -0,0 +1,191 @@
+/**
+ * Draw two quads, one using only a vertex shader, the other only with a
+ * fragment shader.  They should appear the same.
+ * 17 Dec 2008
+ * Brian Paul
+ */
+
+
+#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 char *FragProgFile = NULL;
+static char *VertProgFile = NULL;
+static GLuint FragShader;
+static GLuint VertShader;
+static GLuint VertProgram;  /* w/out vertex shader */
+static GLuint FragProgram;  /* w/out fragment shader */
+static GLint Win = 0;
+
+
+static void
+DrawQuadColor(void)
+{
+   glBegin(GL_QUADS);
+   glColor3f(1, 0, 0);    glVertex2f(-1, -1);
+   glColor3f(0, 1, 0);    glVertex2f( 1, -1);
+   glColor3f(0, 0, 1);    glVertex2f( 1,  1);
+   glColor3f(1, 0, 1);    glVertex2f(-1,  1);
+   glEnd();
+}
+
+
+/** as above, but specify color via texcoords */
+static void
+DrawQuadTex(void)
+{
+   glBegin(GL_QUADS);
+   glTexCoord3f(1, 0, 0);    glVertex2f(-1, -1);
+   glTexCoord3f(0, 1, 0);    glVertex2f( 1, -1);
+   glTexCoord3f(0, 0, 1);    glVertex2f( 1,  1);
+   glTexCoord3f(1, 0, 1);    glVertex2f(-1,  1);
+   glEnd();
+}
+
+
+static void
+Redisplay(void)
+{
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+   /* render with vertex shader only */
+   glUseProgram_func(VertProgram);
+   glPushMatrix();
+   glTranslatef(-1.5, 0, 0);
+   DrawQuadTex();
+   glPopMatrix();
+
+   /* render with fragment shader only */
+   glUseProgram_func(FragProgram);
+   glPushMatrix();
+   glTranslatef(+1.5, 0, 0);
+   DrawQuadColor();
+   glPopMatrix();
+
+   glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+   glViewport(0, 0, width, height);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glOrtho(-4, 4, -2, 2, -1, 1);
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+}
+
+
+static void
+CleanUp(void)
+{
+   glDeleteShader_func(FragShader);
+   glDeleteShader_func(VertShader);
+   glDeleteProgram_func(VertProgram);
+   glDeleteProgram_func(FragProgram);
+   glutDestroyWindow(Win);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+  (void) x;
+  (void) y;
+   switch(key) {
+   case 27:
+      CleanUp();
+      exit(0);
+      break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void
+Init(void)
+{
+   static const char *fragShaderText =
+      "void main() {\n"
+      "   gl_FragColor = gl_Color;\n"
+      "}\n";
+   static const char *vertShaderText =
+      "void main() {\n"
+      "   gl_Position = ftransform();\n"
+      "   gl_FrontColor = gl_MultiTexCoord0;\n" /* see DrawQuadTex() */
+      "}\n";
+
+   if (!ShadersSupported())
+      exit(1);
+
+   GetExtensionFuncs();
+
+   if (FragProgFile)
+      FragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
+   else
+      FragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
+
+   if (VertProgFile)
+      VertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
+   else
+      VertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
+
+   VertProgram = LinkShaders(VertShader, 0);
+   FragProgram = LinkShaders(0, FragShader);
+
+   glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
+   glEnable(GL_DEPTH_TEST);
+
+   printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
+
+   assert(glIsProgram_func(VertProgram));
+   assert(glIsProgram_func(FragProgram));
+   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(400, 200);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+   Win = glutCreateWindow(argv[0]);
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutDisplayFunc(Redisplay);
+   ParseOptions(argc, argv);
+   Init();
+   glutMainLoop();
+   return 0;
+}