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{
Bouncing ball demo. Color index mode only!
This program is in the public domain
Brian Paul
Converted to Pascal by Peter Vreman
}
program bounce;
{$mode objfpc}
uses
gl,glut;
const
RED=1;
WHITE=2;
CYAN=3;
var
IndexMode : Boolean;
Ball : GLuint;
const
Zrot : GLfloat = 0.0;
Zstep : GLfloat = 6.0;
Xpos : GLfloat = 0.0;
Ypos : GLfloat = 1.0;
Xvel : GLfloat = 0.2;
Yvel : GLfloat = 0.0;
Xmin : GLfloat = -4.0;
Xmax : GLfloat = 4.0;
Ymin : GLfloat = -3.8;
Ymax : GLfloat = 4.0;
G : GLfloat = -0.1;
function make_ball:GLuint;
var
list : GLuint;
a,b,
ar,br : GLFloat;
da,db,
dar : GLFloat;
radius : GLFloat;
color : boolean;
x,y,z : GLFloat;
begin
da:=18.0;
db:=18.0;
radius:=1.0;
list := glGenLists(1);
glNewList(list, GL_COMPILE);
color := false;
a:=-90.0;
while (a+da<=90.0) do
begin
glBegin(GL_QUAD_STRIP);
b:=0.0;
while (b<=360.0) do
begin
if (color) then
begin
glIndexi(RED);
glColor3f(1, 0, 0);
end
else
begin
glIndexi(WHITE);
glColor3f(1, 1, 1);
end;
ar:=a * 3.14159/180.0;
br:=b * 3.14159/180.0;
x := COS(br) * COS(ar);
y := SIN(br) * COS(ar);
z := SIN(ar);
glVertex3f(x, y, z);
dar:=da * 3.14159/180.0;
x := radius * COS(br) * COS(ar + dar);
y := radius * SIN(br) * COS(ar + dar);
z := radius * SIN(ar + dar);
glVertex3f(x, y, z);
color := not color;
b:=b+db;
end;
glEnd();
a:=a+da;
end;
glEndList();
make_ball:=list;
end;
procedure reshape(width,height:longint); cdecl;
var
aspect : glFloat;
begin
aspect := glfloat(width) / glfloat(height);
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-6.0 * aspect, 6.0 * aspect, -6.0, 6.0, -6.0, 6.0);
glMatrixMode(GL_MODELVIEW);
end;
procedure key(k:byte;x,y:longint); cdecl;
begin
case k of
27 :
halt(0);
end;
end;
procedure draw; cdecl;
var
i : GLint;
begin
glClear(GL_COLOR_BUFFER_BIT);
glIndexi(CYAN);
glColor3f(0, 1, 1);
glBegin(GL_LINES);
for i:=-5 to 5 do
begin
glVertex2i(i, -5);
glVertex2i(i, 5);
end;
for i:=-5 to 5 do
begin
glVertex2i(-5, i);
glVertex2i(5, i);
end;
for i:=-5 to 5 do
begin
glVertex2i(i, -5);
glVertex2f(i * 1.15, -5.9);
end;
glVertex2f(-5.3, -5.35);
glVertex2f(5.3, -5.35);
glVertex2f(-5.75, -5.9);
glVertex2f(5.75, -5.9);
glEnd();
glPushMatrix();
glTranslatef(Xpos, Ypos, 0.0);
glScalef(2.0, 2.0, 2.0);
glRotatef(8.0, 0.0, 0.0, 1.0);
glRotatef(90.0, 1.0, 0.0, 0.0);
glRotatef(Zrot, 0.0, 0.0, 1.0);
glCallList(Ball);
glPopMatrix();
glFlush();
glutSwapBuffers();
end;
const
vel0 : glfloat = -100.0;
procedure idle; cdecl;
begin
Zrot:=Zrot+Zstep;
Xpos:=Xpos+Xvel;
if (Xpos >= Xmax) then
begin
Xpos := Xmax;
Xvel := -Xvel;
Zstep := -Zstep;
end;
if (Xpos <= Xmin) then
begin
Xpos := Xmin;
Xvel := -Xvel;
Zstep := -Zstep;
end;
Ypos:=Ypos+Yvel;
Yvel:=Yvel+G;
if (Ypos < Ymin) then
begin
Ypos := Ymin;
if (vel0 = -100.0) then
vel0 := abs(Yvel);
Yvel := vel0;
end;
glutPostRedisplay();
end;
procedure visible(vis:longint); cdecl;
begin
if (vis=GLUT_VISIBLE) then
glutIdleFunc(@idle)
else
glutIdleFunc(nil);
end;
begin
glutInit(@argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(600, 450);
if paramcount>1 then
IndexMode:=(paramstr(1)='-ci');
if (IndexMode) then
glutInitDisplayMode(GLUT_INDEX or GLUT_DOUBLE)
else
glutInitDisplayMode(GLUT_RGB or GLUT_DOUBLE);
glutCreateWindow('Bounce');
Ball := make_ball();
glCullFace(GL_BACK);
glEnable(GL_CULL_FACE);
glDisable(GL_DITHER);
glShadeModel(GL_FLAT);
glutDisplayFunc(@draw);
glutReshapeFunc(@reshape);
glutVisibilityFunc(@visible);
glutKeyboardFunc(@key);
if (IndexMode) then
begin
glutSetColor(RED, 1.0, 0.0, 0.0);
glutSetColor(WHITE, 1.0, 1.0, 1.0);
glutSetColor(CYAN, 0.0, 1.0, 1.0);
end;
glutMainLoop();
end.
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