simple fragment shader test

progs/trivial/Makefile

@@ -12,6 +12,7 @@ LIBS = $(APP_LIB_DEPS)
 
 SOURCES = \
 	clear.c \
+	fs-tri.c \
 	line-clip.c \
 	line-cull.c \
 	line-userclip-clip.c \
@@ -138,6 +139,11 @@ readtex.c: $(TOP)/progs/util/readtex.c
 	ln -s $(TOP)/progs/util/readtex.c .
 
 
+fs-tri: fs-tri.c extfuncs.h
+
+
+extfuncs.h:  $(TOP)/progs/util/extfuncs.h
+	cp $< .
 
 
 # Emacs tags

progs/trivial/fs-tri.c

@@ -0,0 +1,207 @@
+/* Test fragment shader */
+
+#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"
+
+
+static GLuint fragShader;
+static GLuint vertShader;
+static GLuint program;
+static GLint win = 0;
+static GLfloat xpos = 0, ypos = 0;
+
+
+static void
+Redisplay(void)
+{
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+   glPushMatrix();
+   glTranslatef(xpos, ypos, 0);
+
+   glBegin(GL_TRIANGLES);
+   glVertex2f(-0.9, -0.9);
+   glVertex2f( 0.9, -0.9);
+   glVertex2f( 0,  0.9);
+   glEnd();
+
+   glPopMatrix();
+
+   glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+   glViewport(0, 0, width, height);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glOrtho(-1, 1, -1, 1, -1, 1);
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+}
+
+
+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 27:
+      CleanUp();
+      exit(0);
+      break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void
+SpecialKey(int key, int x, int y)
+{
+   const GLfloat step = 0.1;
+
+  (void) x;
+  (void) y;
+
+   switch(key) {
+   case GLUT_KEY_UP:
+      ypos += step;
+      break;
+   case GLUT_KEY_DOWN:
+      ypos -= step;
+      break;
+   case GLUT_KEY_LEFT:
+      xpos -= step;
+      break;
+   case GLUT_KEY_RIGHT:
+      xpos += step;
+      break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void
+LoadAndCompileShader(GLuint shader, const char *text)
+{
+   GLint stat;
+
+   glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
+
+   glCompileShader_func(shader);
+
+   glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
+   if (!stat) {
+      GLchar log[1000];
+      GLsizei len;
+      glGetShaderInfoLog_func(shader, 1000, &len, log);
+      fprintf(stderr, "fslight: problem compiling shader:\n%s\n", log);
+      exit(1);
+   }
+}
+
+
+static void
+CheckLink(GLuint prog)
+{
+   GLint stat;
+   glGetProgramiv_func(prog, GL_LINK_STATUS, &stat);
+   if (!stat) {
+      GLchar log[1000];
+      GLsizei len;
+      glGetProgramInfoLog_func(prog, 1000, &len, log);
+      fprintf(stderr, "Linker error:\n%s\n", log);
+   }
+}
+
+
+static void
+Init(void)
+{
+   /* fragment color is a function of fragment position: */
+   static const char *fragShaderText =
+      "void main() {\n"
+      "   gl_FragColor = gl_FragCoord * vec4(0.005); \n"
+      "}\n";
+#if 0
+   static const char *vertShaderText =
+      "varying vec3 normal;\n"
+      "void main() {\n"
+      "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
+      "   normal = gl_NormalMatrix * gl_Normal;\n"
+      "}\n";
+#endif
+   const char *version;
+
+   version = (const char *) glGetString(GL_VERSION);
+   if (version[0] != '2' || version[1] != '.') {
+      printf("This program requires OpenGL 2.x, found %s\n", version);
+      exit(1);
+   }
+
+   GetExtensionFuncs();
+
+   fragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
+   LoadAndCompileShader(fragShader, fragShaderText);
+
+#if 0
+   vertShader = glCreateShader_func(GL_VERTEX_SHADER);
+   LoadAndCompileShader(vertShader, vertShaderText);
+#endif
+
+   program = glCreateProgram_func();
+   glAttachShader_func(program, fragShader);
+#if 0
+   glAttachShader_func(program, vertShader);
+#endif
+   glLinkProgram_func(program);
+   CheckLink(program);
+   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));
+}
+
+
+int
+main(int argc, char *argv[])
+{
+   glutInit(&argc, argv);
+   glutInitWindowPosition( 0, 0);
+   glutInitWindowSize(200, 200);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+   win = glutCreateWindow(argv[0]);
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutSpecialFunc(SpecialKey);
+   glutDisplayFunc(Redisplay);
+   Init();
+   glutMainLoop();
+   return 0;
+}
+
+