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#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;
use OpenGL qw(:all);
use Math::Trig;
use Time::HiRes qw(sleep time);
####### GL HANDLERS
sub handler_resize {
glViewport(0, 0, $_[0], $_[1]);
}
sub handler_idle {
handler_render();
glFlush();
glutSwapBuffers();
sleep(1 / 50);
}
sub init_gl {
glutInit();
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowSize(512, 512);
glutCreateWindow("example");
glutReshapeFunc (\&handler_resize);
glutIdleFunc (\&handler_idle);
glutDisplayFunc (\&handler_render);
}
sub init_vp {
glClearColor(0.0, 0.0, 0.0, 0.0);
glColor3f(1.0, 1.0, 1.0);
glMatrixMode(GL_PROJECTION);
glOrtho(-1.0, 1.0, 1.0, -1.0, 1, -1);
glMatrixMode(GL_TEXTURE);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_TEXTURE_2D);
# glEnable(GL_BLEND);
# glBlendFunc(GL_SRC_ALPHA, GL_ONE);
}
init_gl();
init_vp();
# #########
sub handler_render {
# ...
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glPushMatrix();
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex2f(-1, -1);
glTexCoord2f(0, 1); glVertex2f(-1, 1);
glTexCoord2f(1, 1); glVertex2f( 1, 1);
glTexCoord2f(1, 0); glVertex2f( 1, -1);
glEnd();
glPopMatrix();
}
my $fragment_id = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
glShaderSourceARB_p($fragment_id, << "__END_SHADER__");
void main() {
float dist = length(gl_TexCoord[0].xy - 0.5);
float val = sin(3.141 / (0.001 + 2 * dist)) / 2 + 0.5;
gl_FragColor = vec4(val, val, val, 1.0);
}
__END_SHADER__
glCompileShaderARB($fragment_id);
my $stat = glGetInfoLogARB_p($fragment_id);
print "WARN shader compile $stat\n" if $stat;
my $shader_prog = glCreateProgramObjectARB();
glAttachObjectARB($shader_prog, $fragment_id);
glLinkProgramARB($shader_prog);
if (!glGetObjectParameterivARB_p($shader_prog, GL_OBJECT_LINK_STATUS_ARB)) {
my $stat = glGetInfoLogARB_p($shader_prog);
die("Failed to link shader program: $stat - dying");
}
glUseProgramObjectARB($shader_prog);
glutMainLoop();
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