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#!/usr/bin/perl |
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use OpenGL ":all"; |
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use OpenCL; |
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my $S = $ARGV[0] || 256; # window/texture size, smaller is faster |
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# open a window and create a gl texture |
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OpenGL::glpOpenWindow width => $S, height => $S; |
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my $texid = glGenTextures_p 1; |
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glBindTexture GL_TEXTURE_2D, $texid; |
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glTexImage2D_c GL_TEXTURE_2D, 0, GL_RGBA8, $S, $S, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0; |
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# find and use the first opencl device that let's us get a shared opengl context |
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my $platform; |
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my $dev; |
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my $ctx; |
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for (OpenCL::platforms) { |
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$platform = $_; |
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for ($platform->devices) { |
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$dev = $_; |
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root |
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$ctx = $platform->context (undef, [$dev]) |
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root |
1.1 |
and last; |
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} |
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} |
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$ctx |
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or die "cannot find suitable OpenCL device\n"; |
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my $queue = $ctx->queue ($dev); |
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# now the boring opencl code |
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my $src = <<EOF; |
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kernel void |
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juliatunnel (write_only image2d_t img, float time) |
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{ |
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int2 xy = (int2)(get_global_id (0), get_global_id (1)); |
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float2 p = convert_float2 (xy) / $S.f * 2.f - 1.f; |
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float2 m = (float2)(1.f, p.y) / fabs (p.x); // tunnel |
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m.x = fabs (fmod (m.x + time * 0.05f, 4.f) - 2.f); |
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float2 z = m; |
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float2 c = (float2)(sin (time * 0.01133f), cos (time * 0.02521f)); |
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for (int i = 0; i < 25 && dot (z, z) < 4.f; ++i) // standard julia |
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z = (float2)(z.x * z.x - z.y * z.y, 2.f * z.x * z.y) + c; |
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float3 colour = (float3)(z.x, z.y, atan2 (z.y, z.x)); |
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write_imagef (img, xy, (float4)(colour * p.x * p.x, 1.)); |
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} |
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EOF |
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my $prog = $ctx->build_program ($src); |
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my $kernel = $prog->kernel ("juliatunnel"); |
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my $tex = $ctx->image2d (OpenCL::MEM_WRITE_ONLY, OpenCL::RGBA, OpenCL::UNORM_INT8, $S, $S); |
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# program compiled, kernel ready, now draw and loop |
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for (my $time; ; ++$time) { |
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# configure and run our kernel |
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$kernel->setf ("mf", $tex, $time*2); # mf = memory object, float |
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$queue->nd_range_kernel ($kernel, undef, [$S, $S], undef); |
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# read image |
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$queue->read_image ($tex, 0, 0, 0, 0, $S, $S, 1, 0, 0, my $data); |
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# wait |
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$queue->finish; |
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# upload texture |
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glTexSubImage2D_s GL_TEXTURE_2D, 0, 0, 0, $S, $S, GL_RGBA, GL_UNSIGNED_BYTE, $data; |
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# now draw the texture, the defaults should be all right |
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glTexParameterf GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST; |
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glEnable GL_TEXTURE_2D; |
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glBegin GL_QUADS; |
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glTexCoord2f 0, 1; glVertex3i -1, -1, -1; |
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glTexCoord2f 0, 0; glVertex3i 1, -1, -1; |
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glTexCoord2f 1, 0; glVertex3i 1, 1, -1; |
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glTexCoord2f 1, 1; glVertex3i -1, 1, -1; |
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glEnd; |
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# with glDrawPixels, you would simply do: |
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# glDrawPixels_s $S, $S, GL_RGBA, GL_UNSIGNED_BYTE, $data; |
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# and then start to worry a lot about the coordinate system |
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# used in the opencl kernel |
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glXSwapBuffers; |
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select undef, undef, undef, 1/60; |
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} |
