259 lines
4.7 KiB
C
259 lines
4.7 KiB
C
/**
|
|
* Test variable array indexing in a vertex shader.
|
|
* Brian Paul
|
|
* 17 April 2009
|
|
*/
|
|
|
|
#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"
|
|
|
|
|
|
/**
|
|
* The vertex position.z is used as a (variable) index into an
|
|
* array which returns a new Z value.
|
|
*/
|
|
static const char *VertShaderText =
|
|
"uniform sampler2D tex1; \n"
|
|
"uniform float HeightArray[20]; \n"
|
|
"void main() \n"
|
|
"{ \n"
|
|
" vec4 pos = gl_Vertex; \n"
|
|
" int i = int(pos.z * 9.5); \n"
|
|
" pos.z = HeightArray[i]; \n"
|
|
" gl_Position = gl_ModelViewProjectionMatrix * pos; \n"
|
|
" gl_FrontColor = pos; \n"
|
|
"} \n";
|
|
|
|
static const char *FragShaderText =
|
|
"void main() \n"
|
|
"{ \n"
|
|
" gl_FragColor = gl_Color; \n"
|
|
"} \n";
|
|
|
|
|
|
static GLuint fragShader;
|
|
static GLuint vertShader;
|
|
static GLuint program;
|
|
|
|
static GLint win = 0;
|
|
static GLboolean Anim = GL_TRUE;
|
|
static GLboolean WireFrame = GL_TRUE;
|
|
static GLfloat xRot = -70.0f, yRot = 0.0f, zRot = 0.0f;
|
|
|
|
|
|
static void
|
|
Idle(void)
|
|
{
|
|
zRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.05;
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
/** z=f(x,y) */
|
|
static float
|
|
fz(float x, float y)
|
|
{
|
|
return fabs(cos(1.5*x) + cos(1.5*y));
|
|
}
|
|
|
|
|
|
static void
|
|
DrawMesh(void)
|
|
{
|
|
GLfloat xmin = -2.0, xmax = 2.0;
|
|
GLfloat ymin = -2.0, ymax = 2.0;
|
|
GLuint xdivs = 20, ydivs = 20;
|
|
GLfloat dx = (xmax - xmin) / xdivs;
|
|
GLfloat dy = (ymax - ymin) / ydivs;
|
|
GLfloat ds = 1.0 / xdivs, dt = 1.0 / ydivs;
|
|
GLfloat x, y, s, t;
|
|
GLuint i, j;
|
|
|
|
y = ymin;
|
|
t = 0.0;
|
|
for (i = 0; i < ydivs; i++) {
|
|
x = xmin;
|
|
s = 0.0;
|
|
glBegin(GL_QUAD_STRIP);
|
|
for (j = 0; j < xdivs; j++) {
|
|
float z0 = fz(x, y), z1 = fz(x, y + dy);
|
|
|
|
glTexCoord2f(s, t);
|
|
glVertex3f(x, y, z0);
|
|
|
|
glTexCoord2f(s, t + dt);
|
|
glVertex3f(x, y + dy, z1);
|
|
x += dx;
|
|
s += ds;
|
|
}
|
|
glEnd();
|
|
y += dy;
|
|
t += dt;
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
Redisplay(void)
|
|
{
|
|
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
|
|
|
|
if (WireFrame)
|
|
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
|
|
else
|
|
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
|
|
|
|
glPushMatrix();
|
|
glRotatef(xRot, 1.0f, 0.0f, 0.0f);
|
|
glRotatef(yRot, 0.0f, 1.0f, 0.0f);
|
|
glRotatef(zRot, 0.0f, 0.0f, 1.0f);
|
|
|
|
glPushMatrix();
|
|
DrawMesh();
|
|
glPopMatrix();
|
|
|
|
glPopMatrix();
|
|
|
|
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
|
|
|
|
glutSwapBuffers();
|
|
}
|
|
|
|
|
|
static void
|
|
Reshape(int width, int height)
|
|
{
|
|
glViewport(0, 0, width, height);
|
|
glMatrixMode(GL_PROJECTION);
|
|
glLoadIdentity();
|
|
glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
|
|
glMatrixMode(GL_MODELVIEW);
|
|
glLoadIdentity();
|
|
glTranslatef(0.0f, 0.0f, -15.0f);
|
|
}
|
|
|
|
|
|
static void
|
|
CleanUp(void)
|
|
{
|
|
glDeleteShader(fragShader);
|
|
glDeleteShader(vertShader);
|
|
glDeleteProgram(program);
|
|
glutDestroyWindow(win);
|
|
}
|
|
|
|
|
|
static void
|
|
Key(unsigned char key, int x, int y)
|
|
{
|
|
const GLfloat step = 2.0;
|
|
(void) x;
|
|
(void) y;
|
|
|
|
switch(key) {
|
|
case 'a':
|
|
Anim = !Anim;
|
|
if (Anim)
|
|
glutIdleFunc(Idle);
|
|
else
|
|
glutIdleFunc(NULL);
|
|
break;
|
|
case 'w':
|
|
WireFrame = !WireFrame;
|
|
break;
|
|
case 'z':
|
|
zRot += step;
|
|
break;
|
|
case 'Z':
|
|
zRot -= step;
|
|
break;
|
|
case 27:
|
|
CleanUp();
|
|
exit(0);
|
|
break;
|
|
}
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void
|
|
SpecialKey(int key, int x, int y)
|
|
{
|
|
const GLfloat step = 2.0;
|
|
|
|
(void) x;
|
|
(void) y;
|
|
|
|
switch(key) {
|
|
case GLUT_KEY_UP:
|
|
xRot += step;
|
|
break;
|
|
case GLUT_KEY_DOWN:
|
|
xRot -= step;
|
|
break;
|
|
case GLUT_KEY_LEFT:
|
|
yRot -= step;
|
|
break;
|
|
case GLUT_KEY_RIGHT:
|
|
yRot += step;
|
|
break;
|
|
}
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void
|
|
Init(void)
|
|
{
|
|
GLfloat HeightArray[20];
|
|
GLint u, i;
|
|
|
|
if (!ShadersSupported())
|
|
exit(1);
|
|
|
|
vertShader = CompileShaderText(GL_VERTEX_SHADER, VertShaderText);
|
|
fragShader = CompileShaderText(GL_FRAGMENT_SHADER, FragShaderText);
|
|
program = LinkShaders(vertShader, fragShader);
|
|
|
|
glUseProgram(program);
|
|
|
|
/* Setup the HeightArray[] uniform */
|
|
for (i = 0; i < 20; i++)
|
|
HeightArray[i] = i / 20.0;
|
|
u = glGetUniformLocation(program, "HeightArray");
|
|
glUniform1fv(u, 20, HeightArray);
|
|
|
|
assert(glGetError() == 0);
|
|
|
|
glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
|
|
glEnable(GL_DEPTH_TEST);
|
|
glColor3f(1, 1, 1);
|
|
}
|
|
|
|
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
glutInit(&argc, argv);
|
|
glutInitWindowSize(500, 500);
|
|
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
|
|
win = glutCreateWindow(argv[0]);
|
|
glewInit();
|
|
glutReshapeFunc(Reshape);
|
|
glutKeyboardFunc(Key);
|
|
glutSpecialFunc(SpecialKey);
|
|
glutDisplayFunc(Redisplay);
|
|
Init();
|
|
if (Anim)
|
|
glutIdleFunc(Idle);
|
|
glutMainLoop();
|
|
return 0;
|
|
}
|
|
|