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{
GL units for Free Pascal - GLUT demo
1999 Sebastian Guenther, sguenther@gmx.de
2008 Jonas Maebe (converted to use vertex arrays)
You may use this source as starting point for your own programs; consider it
as Public Domain.
}
{$mode objfpc}
library GLUTDemoES;
uses
gles11, math;
const
FPCImg: array[0..4, 0..10] of Byte =
((1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1),
(1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0),
(1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0),
(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0),
(1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1));
var
counter: Integer;
(*
3 __ 2
/| |
7/0|_ |1
|/ /
+--+
4 5
back plane: 0-3-2-1
*)
const
colors: array[0..7, 0..3] of Single =
((0, 0, 0, 1), (0, 0, 1, 1), (0, 1, 0, 1), (0, 1, 1, 1),
(1, 0, 0, 1), (1, 0, 1, 1), (1, 1, 0, 1), (1, 1, 1, 1));
corners: array[0..7, 0..2] of Single =
((-1, -1, -1), (+1, -1, -1), (+1, +1, -1), (-1, +1, -1),
(-1, -1, +1), (+1, -1, +1), (+1, +1, +1), (-1, +1, +1));
indices: array[0..5] of array[0..3] of GLubyte =
(
{ all vertices must be in ccw order }
(0,3,1,2), // back
(4,5,7,6), // front
(3,0,7,4), // left
(1,2,5,6), // right
(3,7,2,6), // top
(5,4,1,0) // bottom
);
procedure DrawCube;
begin
glEnableClientState(GL_VERTEX_ARRAY);
if (glGetError() <> GL_NO_ERROR) then
halt(10);
glEnableClientState(GL_COLOR_ARRAY);
if (glGetError() <> GL_NO_ERROR) then
halt(11);
glVertexPointer(3,GL_FLOAT,0,@corners);
if (glGetError() <> GL_NO_ERROR) then
halt(12);
glColorPointer(4,GL_FLOAT,0,@colors);
if (glGetError() <> GL_NO_ERROR) then
halt(13);
// this will also draw a bunch of triangles inside the cube, but
// may still be faster than the commented-out sequence below due
// to less calls into the renderer
glDrawElements(GL_TRIANGLE_STRIP,24,GL_UNSIGNED_BYTE,@indices[0]);
if (glGetError() <> GL_NO_ERROR) then
halt(14);
(*
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[0]);
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[1]);
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[2]);
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[3]);
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[4]);
glDrawElements(GL_TRIANGLE_STRIP,4,GL_UNSIGNED_BYTE,@indices[5]);
*)
glDisableClientState(GL_VERTEX_ARRAY);
if (glGetError() <> GL_NO_ERROR) then
halt(15);
glDisableClientState(GL_COLOR_ARRAY);
if (glGetError() <> GL_NO_ERROR) then
halt(16);
end;
procedure glDraw; cdecl; export;
var
x, y: Integer;
begin
Inc(counter);
// counter:=145;
glClearColor(0, 0, 0.2, 1);
if (glGetError() <> GL_NO_ERROR) then
halt(8);
glClear(GL_COLOR_BUFFER_BIT+GL_DEPTH_BUFFER_BIT);
if (glGetError() <> GL_NO_ERROR) then
halt(9);
glPushMatrix;
glTranslatef(0, 0, Sin(Single(counter) / 20.0) * 5.0 - 5.0);
glRotatef(Sin(Single(counter) / 200.0) * 720.0, 0, 1, 0);
glRotatef(counter, 0, 0, 1);
for y := 0 to 4 do
for x := 0 to 10 do
if FPCImg[y, x] > 0 then begin
glPushMatrix;
glRotatef(x * Sin(Single(counter) / 5.0), 0, 1, 0);
glRotatef(y * Sin(Single(counter) / 12.0) * 4.0, 0, 0, 1);
glTranslatef((x - 5) * 1, (2 - y) * 1, 0);
glScalef(0.4, 0.4, 0.4);
glRotatef(counter, 0.5, 1, 0);
DrawCube;
glPopMatrix;
end;
glPopMatrix;
end;
{ gluperspective replacement, from http://iphonedevelopment.blogspot.com/2008/12/gluperspective.html }
procedure gluperspective(fovy, aspect, znear, zfar: GLfloat);
var
xmin, xmax, ymin, ymax: GLfloat;
begin
// Start in projection mode.
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
ymax := zNear * tan(fovy * pi / 360.0);
ymin := -ymax;
xmin := ymin * aspect;
xmax := ymax * aspect;
glfrustumf(xmin, xmax, ymin, ymax, zNear, zFar);
end;
procedure glInit; cdecl; export;
begin
// Enable backface culling
glEnable(GL_CULL_FACE);
if (glGetError() <> GL_NO_ERROR) then
halt(1);
// Set up depth buffer
glEnable(GL_DEPTH_TEST);
if (glGetError() <> GL_NO_ERROR) then
halt(2);
glDepthFunc(GL_LESS);
if (glGetError() <> GL_NO_ERROR) then
halt(3);
// Set up projection matrix
glMatrixMode(GL_PROJECTION);
if (glGetError() <> GL_NO_ERROR) then
halt(4);
glLoadIdentity;
gluPerspective(90, 1.3, 0.1, 100);
if (glGetError() <> GL_NO_ERROR) then
halt(5);
glMatrixMode(GL_MODELVIEW);
if (glGetError() <> GL_NO_ERROR) then
halt(6);
glLoadIdentity;
glTranslatef(0, 0, -5.5);
if (glGetError() <> GL_NO_ERROR) then
halt(7);
end;
end.
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