PSU Capstone Project Candidate: ARB_vertex_program Compiler

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PSU Capstone Project Candidate
ARB_vertex_program Compiler
October 10th, 2005
Ian Romanick (idr_at_us.ibm.com)
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Project Vertex program compiler

• Modern graphics hardware is becoming more
  flexible and general
• First generation of programmable hardware was
  released 4 years ago (Radeon 8500 Geforce3).
• Three complete generations later, and approaching
  complete generality.

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Why vertex programs?

• Allow offloading of complex effects from the host
  CPU to the graphics processor (GPU).
• Processing data on GPU can eliminate need to
  transfer data each frame.
• New opportunities for hardware optimization.
• Exposed via APIs such as OpenGL or DirectX.
• Serveral common extensions to OpenGL.
• ARB_vertex_program, ARB_vertex_shader,
  NV_vertex_program
• Core feature in OpenGL 2.0.
• Core feature in DirectX 8.1 and later.

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Vertex program demo

• All calculations happen in the vertex program.
• Only the position of the gravity point is
  modified each frame.
• Compute distance from vertex to gravity source
• ADD R1, program.local30, -vertex.position
  vector from vertex to gravity
• DP3 R2, R1, R1 dot product
• RSQ R2, R2.x square root distance
• MUL R2, R2, program.local31.xxxx scale
  by the gravity factor
• MAD R3, R1, R2, vertex.position Displace
  vertex by gravity
• Continue with typical modelview/projection
• DP4 result.position.x, state.matrix.mvp.row0,
  R3 object x MVP -gt clip
• DP4 result.position.y, state.matrix.mvp.row1,
  R3
• DP4 result.position.z, state.matrix.mvp.row2,
  R3
• DP4 result.position.w, state.matrix.mvp.row3,
  R3
• MOV result.color, vertex.color copy input
  color to output color

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Not all GPUs run vertex programs

• All pre-2001 GPUs and some later GPUs don't
  support vertex programs.
• Embedded GPUs save chip space by using host CPU
  for vertex programs.
• Example Sony PSP, Nintendo DS
• Integrated GPUs (embedded in motherboard
  chipset) often don't support vertex programs.
• Example Intel i945G

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OpenGL on Linux

• All open-source 3D drivers for Linux are based on
  Mesa.
• Mesa supports ARB_vertex_program.
• Programs are compiled to byte code (not Java).
• At run-time, byte code is...interpreted!
• Painfullly slow!
• No cards supported by open-source drivers have
  native vertex program support.
• To achieve acceptable performance, a compiler
  targeted for the host CPU is needed.

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Project requirements

• Write compiler back-end for ARB_vertex_program.
• Front-end already exists.
• Only target one common CPU (e.g., x86, x86-64,
  PowerPC, etc.)
• Project done when some agreed upon set of
  programs compiles and runs correctly.
• Performance need not be optimial.

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Skills needed / Assistance Provided

• Strong C programming skills.
• Compiler skills...remember CS322???
• Working knowledge of SIMD computing a big plus.
• OpenGL knowledge is a plus, but not requiremed.
• Can meet with students on weekly basis or anytime
  via e-mail / IRC.
• Assist understanding existing code.
• Assist with instruction set issues.
• Can provide samples and tests.
• All required documentation available on the web.

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Questions?
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Legal Statement

• This work represents the views of the author(s)
  and does not necessarily reflect the views of IBM
  Corporation.
• The following terms are trademarks or registered
  trademarks of International Business Machines
  Corporation in the United States and/or other
  countries IBM (logo). A full list of U.S.
  trademarks owned by IBM may be found at
  http//www.ibm.com/legal/copytrade.shtml.
• OpenGL is a trademark of SGI.
• DirectX is a trademark of Microsoft.
• Linux is a registered trademark of Linus
  Torvalds.
• Other company, product, and service names may be
  trademarks or service marks of others.