Added shader points and shader bitmap demos

1 files changed, 301 insertions, 0 deletions

diff --git a/progs/glsl/points.c b/progs/glsl/points.c
new file mode 100644
index 0000000000..2dc0670c60
--- /dev/null
+++ b/progs/glsl/points.c
@@ -0,0 +1,301 @@
+/**
+ * Implement smooth (AA) points with shaders.
+ * A simple variation could be used for sprite points.
+ * Brian Paul
+ * 29 July 2007
+ */
+
+#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 GLint WinWidth = 500, WinHeight = 200;
+static GLfloat Xpos = 0.0f, Ypos = 0.0f;
+static GLint uViewportInv;
+static GLboolean Smooth = GL_TRUE, Blend = GL_TRUE;
+
+
+/**
+ * Issue vertices for a "shader point".
+ * The position is duplicated, only texcoords (or other vertex attrib) change.
+ * The vertex program will compute the "real" quad corners.
+ */
+static void
+PointVertex3f(GLfloat x, GLfloat y, GLfloat z)
+{
+   glTexCoord2f(-1, -1);
+   glVertex3f(x, y, z);
+
+   glTexCoord2f( 1, -1);
+   glVertex3f(x, y, z);
+
+   glTexCoord2f( 1,  1);
+   glVertex3f(x, y, z);
+
+   glTexCoord2f(-1,  1);
+   glVertex3f(x, y, z);
+}
+
+
+static void
+DrawPoints(GLboolean shaderPoints)
+{
+   int i;
+   for (i = 0; i < 9; i++) {
+      GLfloat x = i - 4, y = 0, z = 0;
+      /* note: can't call glPointSize inside Begin/End :( */
+      glPointSize( 2 + i * 5 );
+      if (shaderPoints) {
+         glBegin(GL_QUADS);
+         PointVertex3f(x, y, z);
+         glEnd();
+      }
+      else {
+         glBegin(GL_POINTS);
+         glVertex3f(x, y, z);
+         glEnd();
+      }
+   }
+}
+
+
+/**
+ * Top row of points rendered convetionally,
+ * bottom row rendered with shaders.
+ */
+static void
+Redisplay(void)
+{
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+   if (Smooth)
+      glEnable(GL_POINT_SMOOTH);
+   else
+      glDisable(GL_POINT_SMOOTH);
+
+   if (Blend)
+      glEnable(GL_BLEND);
+   else
+      glDisable(GL_BLEND);
+
+   glPushMatrix();
+   glTranslatef(Xpos, Ypos, 0);
+
+   /*
+    * regular points
+    */
+   glPushMatrix();
+   glTranslatef(0, 1.2, 0);
+   glUseProgram_func(0);
+   DrawPoints(GL_FALSE);
+   glPopMatrix();
+
+   /*
+    * shader points
+    */
+   glPushMatrix();
+   glTranslatef(0, -1.2, 0);
+   glUseProgram_func(Program);
+   if (uViewportInv != -1) {
+      glUniform2f_func(uViewportInv, 1.0 / WinWidth, 1.0 / WinHeight);
+   }
+   DrawPoints(GL_TRUE);
+   glPopMatrix();
+
+   glPopMatrix();
+
+   glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+   WinWidth = width;
+   WinHeight = height;
+   glViewport(0, 0, width, height);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glFrustum(-1.0, 1.0, -1.0, 1.0, 4.0, 30.0);
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+   glTranslatef(0.0f, 0.0f, -20.0f);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+  (void) x;
+  (void) y;
+
+   switch(key) {
+   case 'b':
+      Blend = !Blend;
+      break;
+   case 's':
+      Smooth = !Smooth;
+      break;
+   case 27:
+      glDeleteShader_func(FragShader);
+      glDeleteShader_func(VertShader);
+      glDeleteProgram_func(Program);
+      glutDestroyWindow(Win);
+      exit(0);
+   }
+   glutPostRedisplay();
+}
+
+
+static void
+SpecialKey(int key, int x, int y)
+{
+   const GLfloat step = 1/100.0;
+   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 shader: compute distance of fragment from center of point,
+    * if dist > 1, discard
+    * if dist < k, coverage = 1
+    * else, coverage = func(dist)
+    */
+   static const char *fragShaderText =
+      "void main() {\n"
+      "   float cover; \n"
+      "   float k = 2.0 / gl_Point.size; \n"
+      "   float d = length(gl_TexCoord[0].xy); \n"
+      "   if (d >= 1.0) \n"
+      "      discard; \n"
+      "   if (d < 1.0 - k) \n"
+      "      cover = 1.0; \n"
+      "   else \n"
+      "      cover = (1.0 - d) * 0.5 * gl_Point.size; \n"
+      "   gl_FragColor.rgb = gl_Color.rgb; \n"
+      "   gl_FragColor.a = cover; \n"
+      "}\n";
+   /* Vertex shader: compute new vertex position based on incoming vertex pos,
+    * texcoords and inverse viewport scale factor.
+    */
+   static const char *vertShaderText =
+      "uniform vec2 viewportInv; \n"
+      "void main() {\n"
+      "   vec4 p = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
+      "   vec2 scale2 = viewportInv * gl_Point.size; \n"
+      "   gl_Position.xy = p.xy + gl_MultiTexCoord0.xy * scale2 * p.w; \n"
+      "   gl_Position.zw = p.zw; \n"
+      "   gl_TexCoord[0] = gl_MultiTexCoord0; \n"
+      "   gl_FrontColor = gl_Color; \n"
+      "}\n";
+   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);
+   }
+   printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
+
+   GetExtensionFuncs();
+
+   FragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
+   LoadAndCompileShader(FragShader, fragShaderText);
+
+   VertShader = glCreateShader_func(GL_VERTEX_SHADER);
+   LoadAndCompileShader(VertShader, vertShaderText);
+
+   Program = glCreateProgram_func();
+   glAttachShader_func(Program, FragShader);
+   glAttachShader_func(Program, VertShader);
+   glLinkProgram_func(Program);
+   CheckLink(Program);
+   glUseProgram_func(Program);
+
+   uViewportInv = glGetUniformLocation_func(Program, "viewportInv");
+
+   glUseProgram_func(0);
+
+   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+   glutInit(&argc, argv);
+   glutInitWindowSize(WinWidth, WinHeight);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+   Win = glutCreateWindow(argv[0]);
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutSpecialFunc(SpecialKey);
+   glutDisplayFunc(Redisplay);
+   Init();
+   glutMainLoop();
+   return 0;
+}
+
+