/*
lightposition.c
Nate Robins, 1997
Tool for teaching about OpenGL light positioning.
*/
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include "glm.h"
typedef struct _cell {
int id;
int x, y;
float min, max;
float value;
float step;
char* info;
char* format;
} cell;
cell lookat[9] = {
{ 1, 180, 120, -5.0, 5.0, 0.0, 0.1,
"Specifies the X position of the eye point.", "%.2f" },
{ 2, 240, 120, -5.0, 5.0, 0.0, 0.1,
"Specifies the Y position of the eye point.", "%.2f" },
{ 3, 300, 120, -5.0, 5.0, 2.0, 0.1,
"Specifies the Z position of the eye point.", "%.2f" },
{ 4, 180, 160, -5.0, 5.0, 0.0, 0.1,
"Specifies the X position of the reference point.", "%.2f" },
{ 5, 240, 160, -5.0, 5.0, 0.0, 0.1,
"Specifies the Y position of the reference point.", "%.2f" },
{ 6, 300, 160, -5.0, 5.0, 0.0, 0.1,
"Specifies the Z position of the reference point.", "%.2f" },
{ 7, 180, 200, -2.0, 2.0, 0.0, 0.1,
"Specifies the X direction of the up vector.", "%.2f" },
{ 8, 240, 200, -2.0, 2.0, 1.0, 0.1,
"Specifies the Y direction of the up vector.", "%.2f" },
{ 9, 300, 200, -2.0, 2.0, 0.0, 0.1,
"Specifies the Z direction of the up vector.", "%.2f" },
};
cell light[4] = {
{ 10, 180, 40, -5.0, 5.0, 1.5, 0.1,
"Specifies X coordinate of light vector.", "%.2f" },
{ 11, 240, 40, -5.0, 5.0, 1.0, 0.1,
"Specifies Y coordinate of light vector.", "%.2f" },
{ 12, 300, 40, -5.0, 5.0, 1.0, 0.1,
"Specifies Z coordinate of light vector.", "%.2f" },
{ 13, 360, 40, 0.0, 1.0, 0.0, 1.0,
"Specifies directional (0) or positional (1) light.", "%.2f" }
};
GLboolean swapped = GL_FALSE;
GLboolean world_draw = GL_TRUE;
GLMmodel* pmodel = NULL;
GLint selection = 0;
void redisplay_all(void);
GLdouble projection[16], modelview[16], inverse[16];
GLuint window, world, screen, command;
GLuint sub_width = 256, sub_height = 256;
GLvoid *font_style = GLUT_BITMAP_TIMES_ROMAN_10;
void
setfont(char* name, int size)
{
font_style = GLUT_BITMAP_HELVETICA_10;
if (strcmp(name, "helvetica") == 0) {
if (size == 12)
font_style = GLUT_BITMAP_HELVETICA_12;
else if (size == 18)
font_style = GLUT_BITMAP_HELVETICA_18;
} else if (strcmp(name, "times roman") == 0) {
font_style = GLUT_BITMAP_TIMES_ROMAN_10;
if (size == 24)
font_style = GLUT_BITMAP_TIMES_ROMAN_24;
} else if (strcmp(name, "8x13") == 0) {
font_style = GLUT_BITMAP_8_BY_13;
} else if (strcmp(name, "9x15") == 0) {
font_style = GLUT_BITMAP_9_BY_15;
}
}
void
drawstr(GLuint x, GLuint y, char* format, ...)
{
va_list args;
char buffer[255], *s;
va_start(args, format);
vsprintf(buffer, format, args);
va_end(args);
glRasterPos2i(x, y);
for (s = buffer; *s; s++)
glutBitmapCharacter(font_style, *s);
}
void
cell_draw(cell* cell)
{
glColor3ub(0, 255, 128);
if (selection == cell->id) {
glColor3ub(255, 255, 0);
drawstr(10, 240, cell->info);
glColor3ub(255, 0, 0);
}
drawstr(cell->x, cell->y, cell->format, cell->value);
}
int
cell_hit(cell* cell, int x, int y)
{
if (x > cell->x && x < cell->x + 60 &&
y > cell->y-30 && y < cell->y+10)
return cell->id;
return 0;
}
void
cell_update(cell* cell, int update)
{
if (selection != cell->id)
return;
cell->value += update * cell->step;
if (cell->value < cell->min)
cell->value = cell->min;
else if (cell->value > cell->max)
cell->value = cell->max;
}
void
cell_vector(float* dst, cell* cell, int num)
{
while (--num >= 0)
dst[num] = cell[num].value;
}
void
drawmodel(void)
{
if (!pmodel) {
pmodel = glmReadOBJ("data/soccerball.obj");
if (!pmodel) exit(0);
glmUnitize(pmodel);
glmFacetNormals(pmodel);
glmVertexNormals(pmodel, 90.0);
}
glmDraw(pmodel, GLM_SMOOTH | GLM_MATERIAL);
}
void
drawaxes(void)
{
glColor3ub(255, 0, 0);
glBegin(GL_LINE_STRIP);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.0, 0.0, 0.0);
glVertex3f(0.75, 0.25, 0.0);
glVertex3f(0.75, -0.25, 0.0);
glVertex3f(1.0, 0.0, 0.0);
glVertex3f(0.75, 0.0, 0.25);
glVertex3f(0.75, 0.0, -0.25);
glVertex3f(1.0, 0.0, 0.0);
glEnd();
glBegin(GL_LINE_STRIP);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(0.0, 1.0, 0.0);
glVertex3f(0.0, 0.75, 0.25);
glVertex3f(0.0, 0.75, -0.25);
glVertex3f(0.0, 1.0, 0.0);
glVertex3f(0.25, 0.75, 0.0);
glVertex3f(-0.25, 0.75, 0.0);
glVertex3f(0.0, 1.0, 0.0);
glEnd();
glBegin(GL_LINE_STRIP);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(0.0, 0.0, 1.0);
glVertex3f(0.25, 0.0, 0.75);
glVertex3f(-0.25, 0.0, 0.75);
glVertex3f(0.0, 0.0, 1.0);
glVertex3f(0.0, 0.25, 0.75);
glVertex3f(0.0, -0.25, 0.75);
glVertex3f(0.0, 0.0, 1.0);
glEnd();
glColor3ub(255, 255, 0);
glRasterPos3f(1.1, 0.0, 0.0);
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, 'x');
glRasterPos3f(0.0, 1.1, 0.0);
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, 'y');
glRasterPos3f(0.0, 0.0, 1.1);
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, 'z');
}
void
identity(GLdouble m[16])
{
m[0+4*0] = 1; m[0+4*1] = 0; m[0+4*2] = 0; m[0+4*3] = 0;
m[1+4*0] = 0; m[1+4*1] = 1; m[1+4*2] = 0; m[1+4*3] = 0;
m[2+4*0] = 0; m[2+4*1] = 0; m[2+4*2] = 1; m[2+4*3] = 0;
m[3+4*0] = 0; m[3+4*1] = 0; m[3+4*2] = 0; m[3+4*3] = 1;
}
GLboolean
invert(GLdouble src[16], GLdouble inverse[16])
{
double t;
int i, j, k, swap;
GLdouble tmp[4][4];
identity(inverse);
for (i = 0; i < 4; i++) {
for (j = 0; j < 4; j++) {
tmp[i][j] = src[i*4+j];
}
}
for (i = 0; i < 4; i++) {
/* look for largest element in column. */
swap = i;
for (j = i + 1; j < 4; j++) {
if (fabs(tmp[j][i]) > fabs(tmp[i][i])) {
swap = j;
}
}
if (swap != i) {
/* swap rows. */
for (k = 0; k < 4; k++) {
t = tmp[i][k];
tmp[i][k] = tmp[swap][k];
tmp[swap][k] = t;
t = inverse[i*4+k];
inverse[i*4+k] = inverse[swap*4+k];
inverse[swap*4+k] = t;
}
}
if (tmp[i][i] == 0) {
/* no non-zero pivot. the matrix is singular, which
shouldn't happen. This means the user gave us a bad
matrix. */
return GL_FALSE;
}
t = tmp[i][i];
for (k = 0; k < 4; k++) {
tmp[i][k] /= t;
inverse[i*4+k] /= t;
}
for (j = 0; j < 4; j++) {
if (j != i) {
t = tmp[j][i];
for (k = 0; k < 4; k++) {
tmp[j][k] -= tmp[i][k]*t;
inverse[j*4+k] -= inverse[i*4+k]*t;
}
}
}
}
return GL_TRUE;
}
float
normalize(float* v)
{
float length;
length = sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
v[0] /= length;
v[1] /= length;
v[2] /= length;
return length;
}
void
main_reshape(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, width, height, 0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
#define GAP 25 /* gap between subwindows */
sub_width = (width-GAP*3)/2.0;
sub_height = (height-GAP*3)/2.0;
glutSetWindow(world);
glutPositionWindow(GAP, GAP);
glutReshapeWindow(sub_width, sub_height);
glutSetWindow(screen);
glutPositionWindow(GAP+sub_width+GAP, GAP);
glutReshapeWindow(sub_width, sub_height);
gl
