+++ /dev/null
-/**
- * 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/glew.h>
-#include <GL/glut.h>
-#include "shaderutil.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 is rendered conventionally with GL_POINT_SMOOTH.
- * Bottom row is rendered with special vertex/fragment shaders (see Init()).
- */
-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(0);
- DrawPoints(GL_FALSE);
- glPopMatrix();
-
- /*
- * shader points
- */
- glPushMatrix();
- glTranslatef(0, -1.2, 0);
- glUseProgram(Program);
- if (uViewportInv != -1) {
- glUniform2f(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(FragShader);
- glDeleteShader(VertShader);
- glDeleteProgram(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
-Init(void)
-{
- /* Fragment shader: compute distance of fragment from center of point
- * (we're using texcoords but another varying could be used).
- * if dist > 1, discard (coverage==0)
- * if dist < k, coverage = 1
- * else, coverage = func(dist)
- * Note: length() uses sqrt() and may be expensive. The distance could
- * be squared instead (with adjustments to the threshold (k) test)
- */
- 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, point size, and inverse viewport scale factor.
- * Note: should compute point size attenuation here too.
- */
- static const char *vertShaderText =
- "uniform vec2 viewportInv; \n"
- "void main() {\n"
- " vec4 pos = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
- " gl_Position.xy = pos.xy + gl_MultiTexCoord0.xy * viewportInv \n"
- " * gl_Point.size * pos.w; \n"
- " gl_Position.zw = pos.zw; \n"
- " gl_TexCoord[0] = gl_MultiTexCoord0; \n"
- " gl_FrontColor = gl_Color; \n"
- "}\n";
-
- if (!ShadersSupported())
- exit(1);
-
- VertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
- FragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
- Program = LinkShaders(VertShader, FragShader);
-
- glUseProgram(Program);
-
- uViewportInv = glGetUniformLocation(Program, "viewportInv");
-
- glUseProgram(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]);
- glewInit();
- glutReshapeFunc(Reshape);
- glutKeyboardFunc(Key);
- glutSpecialFunc(SpecialKey);
- glutDisplayFunc(Redisplay);
- Init();
- glutMainLoop();
- return 0;
-}
-
-
projects / mesa.git / blobdiff