1 files changed, 369 insertions, 0 deletions
diff --git a/progs/glsl/texaaline.c b/progs/glsl/texaaline.c
new file mode 100644
index 0000000000..7a5ac405bb
--- /dev/null
+++ b/progs/glsl/texaaline.c
@@ -0,0 +1,369 @@
+/**
+ * AA lines with texture mapped quads
+ *
+ * Brian Paul
+ * 9 Feb 2008
+ */
+
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glew.h>
+#include <GL/glut.h>
+
+
+static GLint WinWidth = 300, WinHeight = 300;
+static GLint win = 0;
+static GLfloat Width = 8.;
+
+/*
+ * Quad strip for line from v0 to v1:
+ *
+ 1   3                     5   7
+ +---+---------------------+---+
+ |                             |
+ |   *v0                 v1*   |
+ |                             |
+ +---+---------------------+---+
+ 0   2                     4   6
+ */
+static void
+QuadLine(const GLfloat *v0, const GLfloat *v1, GLfloat width)
+{
+   GLfloat dx = v1[0] - v0[0];
+   GLfloat dy = v1[1] - v0[1];
+   GLfloat len = sqrt(dx*dx + dy*dy);
+   float dx0, dx1, dx2, dx3, dx4, dx5, dx6, dx7;
+   float dy0, dy1, dy2, dy3, dy4, dy5, dy6, dy7;
+
+   dx /= len;
+   dy /= len;
+
+   width *= 0.5;  /* half width */
+   dx = dx * (width + 0.0);
+   dy = dy * (width + 0.0);
+
+   dx0 = -dx+dy;  dy0 = -dy-dx;
+   dx1 = -dx-dy;  dy1 = -dy+dx;
+
+   dx2 =   0+dy;  dy2 = -dx+0;
+   dx3 =   0-dy;  dy3 = +dx+0;
+
+   dx4 =   0+dy;  dy4 = -dx+0;
+   dx5 =   0-dy;  dy5 = +dx+0;
+
+   dx6 =  dx+dy;  dy6 =  dy-dx;
+   dx7 =  dx-dy;  dy7 =  dy+dx;
+
+   /*
+   printf("dx, dy = %g, %g\n", dx, dy);
+   printf("  dx0, dy0: %g, %g\n", dx0, dy0);
+   printf("  dx1, dy1: %g, %g\n", dx1, dy1);
+   printf("  dx2, dy2: %g, %g\n", dx2, dy2);
+   printf("  dx3, dy3: %g, %g\n", dx3, dy3);
+   */
+
+   glBegin(GL_QUAD_STRIP);
+   glTexCoord2f(0, 0);
+   glVertex2f(v0[0] + dx0, v0[1] + dy0);
+   glTexCoord2f(0, 1);
+   glVertex2f(v0[0] + dx1, v0[1] + dy1);
+
+   glTexCoord2f(0.5, 0);
+   glVertex2f(v0[0] + dx2, v0[1] + dy2);
+   glTexCoord2f(0.5, 1);
+   glVertex2f(v0[0] + dx3, v0[1] + dy3);
+
+   glTexCoord2f(0.5, 0);
+   glVertex2f(v1[0] + dx2, v1[1] + dy2);
+   glTexCoord2f(0.5, 1);
+   glVertex2f(v1[0] + dx3, v1[1] + dy3);
+
+   glTexCoord2f(1, 0);
+   glVertex2f(v1[0] + dx6, v1[1] + dy6);
+   glTexCoord2f(1, 1);
+   glVertex2f(v1[0] + dx7, v1[1] + dy7);
+   glEnd();
+}
+
+
+static float Cos(float a)
+{
+   return cos(a * M_PI / 180.);
+}
+
+static float Sin(float a)
+{
+   return sin(a * M_PI / 180.);
+}
+
+static void
+Redisplay(void)
+{
+   float cx = 0.5 * WinWidth, cy = 0.5 * WinHeight;
+   float len = 0.5 * WinWidth - 20.0;
+   int i;
+
+   glClear(GL_COLOR_BUFFER_BIT);
+
+   glColor3f(1, 1, 1);
+
+   glEnable(GL_BLEND);
+   glEnable(GL_TEXTURE_2D);
+
+   for (i = 0; i < 360; i+=5) {
+      float v0[2], v1[2];
+      v0[0] = cx + 40 * Cos(i);
+      v0[1] = cy + 40 * Sin(i);
+      v1[0] = cx + len * Cos(i);
+      v1[1] = cy + len * Sin(i);
+      QuadLine(v0, v1, Width);
+   }
+
+   {
+      float v0[2], v1[2], x;
+      for (x = 0; x < 1.0; x += 0.2) {
+         v0[0] = cx + x;
+         v0[1] = cy + x * 40 - 20;
+         v1[0] = cx + x + 5.0;
+         v1[1] = cy + x * 40 - 20;
+         QuadLine(v0, v1, Width);
+      }
+   }
+
+   glDisable(GL_BLEND);
+   glDisable(GL_TEXTURE_2D);
+
+   glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+   WinWidth = width;
+   WinHeight = height;
+   glViewport(0, 0, width, height);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glOrtho(0, width, 0, height, -1, 1);
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+}
+
+
+static void
+CleanUp(void)
+{
+   glutDestroyWindow(win);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+  (void) x;
+  (void) y;
+
+   switch(key) {
+   case 'w':
+      Width -= 0.5;
+      break;
+   case 'W':
+      Width += 0.5;
+      break;
+   case 27:
+      CleanUp();
+      exit(0);
+      break;
+   }
+#if 0
+   if (Width < 3)
+      Width = 3;
+#endif
+   printf("Width = %g\n", Width);
+   glutPostRedisplay();
+}
+
+
+static float
+ramp4(GLint i, GLint size)
+{
+   float d;
+   if (i < 4 ) {
+      d = i / 4.0;
+   }
+   else if (i >= size - 5) {
+      d = 1.0 - (i - (size - 5)) / 4.0;
+   }
+   else {
+      d = 1.0;
+   }
+   return d;
+}
+
+static float
+ramp2(GLint i, GLint size)
+{
+   float d;
+   if (i < 2 ) {
+      d = i / 2.0;
+   }
+   else if (i >= size - 3) {
+      d = 1.0 - (i - (size - 3)) / 2.0;
+   }
+   else {
+      d = 1.0;
+   }
+   return d;
+}
+
+static float
+ramp1(GLint i, GLint size)
+{
+   float d;
+   if (i == 0 || i == size-1) {
+      d = 0.0;
+   }
+   else {
+      d = 1.0;
+   }
+   return d;
+}
+
+
+/**
+ * Make an alpha texture for antialiasing lines.
+ * Just a linear fall-off ramp for now.
+ * Should have a number of different textures for different line widths.
+ * Could try a bell-like-curve....
+ */
+static void
+MakeTexture(void)
+{
+#define SZ 8
+   GLfloat tex[SZ][SZ];  /* alpha tex */
+   int i, j;
+   for (i = 0; i < SZ; i++) {
+      for (j = 0; j < SZ; j++) {
+#if 0
+         float k = (SZ-1) / 2.0;
+         float dx = fabs(i - k) / k;
+         float dy = fabs(j - k) / k;
+         float d;
+
+         dx = 1.0 - dx;
+         dy = 1.0 - dy;
+         d = dx * dy;
+
+#else
+         float d = ramp1(i, SZ) * ramp1(j, SZ);
+         printf("%d, %d: %g\n", i, j, d);
+#endif
+         tex[i][j] = d;
+      }
+   }
+
+   glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, SZ, SZ, 0, GL_ALPHA, GL_FLOAT, tex);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+#undef SZ
+}
+
+
+static void
+MakeMipmap(void)
+{
+#define SZ 64
+   GLfloat tex[SZ][SZ];  /* alpha tex */
+   int level;
+
+   glPixelStorei(GL_UNPACK_ROW_LENGTH, SZ);
+   for (level = 0; level < 7; level++) {
+      int sz = 1 << (6 - level);
+      int i, j;
+      for (i = 0; i < sz; i++) {
+         for (j = 0; j < sz; j++) {
+            if (level == 6)
+               tex[i][j] = 1.0;
+            else if (level == 5)
+               tex[i][j] = 0.5;
+            else
+               tex[i][j] = ramp1(i, sz) * ramp1(j, sz);
+         }
+      }
+
+      glTexImage2D(GL_TEXTURE_2D, level, GL_ALPHA,
+                   sz, sz, 0, GL_ALPHA, GL_FLOAT, tex);
+   }
+
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+   //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 4);
+   ////glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 5);
+
+   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+#undef SZ
+}
+
+
+static void
+Init(void)
+{
+   const char *version;
+
+   (void) MakeTexture;
+   (void) ramp4;
+   (void) ramp2;
+
+   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);
+   }
+
+   glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
+
+   printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
+
+   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+#if 0
+   glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+#elif 0
+   MakeTexture();
+#else
+   MakeMipmap();
+#endif
+}
+
+
+static void
+ParseOptions(int argc, char *argv[])
+{
+}
+
+
+int
+main(int argc, char *argv[])
+{
+   glutInit(&argc, argv);
+   glutInitWindowSize(WinWidth, WinHeight);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
+   win = glutCreateWindow(argv[0]);
+   glewInit();
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutDisplayFunc(Redisplay);
+   ParseOptions(argc, argv);
+   Init();
+   glutMainLoop();
+   return 0;
+}