OpenGL SC

© Copyright Khronos Group, 2012 -

OpenGL SC: differences to OpenGL ES

Nakhoon Baek CTO, Mobile Graphics Inc., Korea

Professor, Kyungpook National University, Korea


OpenGL SC


Safety Critical – OpenGL SC 1.0 • targeted at safety-certified avionics and automotive displays

- minimum driver size and complexity

- DO-178B certification

•working group:

- Seaweed (now, Presagis)

- Barco

- ALT Software

- Diehl Aerospace

- Esmertec (now, Myriad Group)

- 3DLabs (now, ZiiLABS)

- Quantum3D

http://mobilegraphics.co.kr/ 3


Military & Avionics: the major market


OpenGL SC 1.0 • originally, OpenGL ES Security Critical Profile

- started as a variation of OpenGL ES

• spin out as OpenGL SC 1.0



OpenGL SC features

• based on OpenGL 1.3

• extinguished features (w.r.t. OpenGL ES)

- glBegin / glEnd paradigm

- display support : a kind of script

• recently,

- OpenGL SC 1.0 conformance test suites

- discussions on the next version (F2F meeting in this Oct.) - OpenGL SC 1.1 ?

- OpenGL SC 2.0 ?



Relationships

• OpenGL 1.3 OpenGL ES 1.0

OpenGL SC 1.0

• OpenGL 1.5 OpenGL ES 1.1

• OpenGL 2.0 + extra features

OpenGL ES 2.0

• OpenGL 3.x OpenGL ES 3.0 (Halti) Expected



Certifications for Airborne Systems

8 mobile graphics lab@KNU


DO-178B • DO-178B, Software Considerations in Airborne Systems and Equipment

Certification

- from RTCA, Inc. (Radio Technical Commission for Aeronautics)

- FAA (Federal Aviation Administration) 인증

- goal: guidance to determine if the software will perform safely and

reliably, in an airborne environment

• also known as ED-12B

- from EUROCAE (European Organization for Civil Aviation Equipment)

mobile graphics lab@KNU 9


DO-178B : software levels • Catastrophic - Failure may cause a crash.

• Hazardous - Failure has a large negative impact on safety or performance

•Major - Failure is significant, but has a lesser impact than a Hazardous

failure

•Minor - Failure is noticeable, but has a lesser impact than a Major failure

• No Effect - Failure has no impact on safety, aircraft operation, or crew

workload.



DO-178B : process • from Software Engineering point of view,

• lots of documents !

• at Planning Stage,

- Plan for software aspects of certification (PSAC)

- Software development plan (SDP)

- Software verification plan (SVP)

- Software configuration management plan (SCMP)

- Software quality assurance plan (SQAP)

- System requirements

- Software requirements standards

- Software design standards (SDS)

- Software code standards (SCS)



DO-178B : process • Development stage,

- Software requirements data (SRD)

- Software design description (SDD)

- Source code

- Executable object code

• Verification stage,

- Software verification cases and procedures (SVCP)

- Software verification results (SVR):

- Review of all requirements, design and code

- Testing of executable object code

- Code coverage analysis



DO-178B : process • Configuration management

- Software configuration index (SCI)

- Software life cycle environment configuration index (SECI)

• Quality Assurance

- Software quality assurance records (SQAR)

- Software conformity review (SCR)

- Software accomplishment summary (SAS)



SC components


OpenGL SC core features

• OpenGL SC core functions: totally 101 functions

- 32 functions are completely new features w.r.t. OpenGL ES

- glBegin / glEnd paradigm

- glVertex functions

- display list support : a kind of script



Core Addition

• OES_single_precision extension

- DepthRangef(clampf n, clampf f)

- Frustumf(float l, float r, float b, float t, float n, float f)

- Orthof(float l, float r, float b, float t, float n, float f)

- ClearDepthf(clampf depth)

- allowing float-type parameters, rather than double-type



Required Extension

• EXT_paletted_texture

- color-indexed texture + color table (or, palette)

- need COLOR_INDEX8_EXT extension support for texturing functions

- need some extensions into the TexImage2D function

- ColorTableEXT

- ColorSubTableEXT

- GetColorTableEXT

- GetColorTableParameterivEXT



Optional Extension

• EXT_shared_texture_palette

- several textures can share a single texture palette

- need some extensions to Enable, Disable, IsEnabled, GetBooleanv, GetFloatv,

GetIntegerv functions

- ColorTableEXT

- ColorSubTableEXT

- GetColorTableEXT

- GetColorTableParameterivEXT



Technical Issues • new implementations are needed for:

- required extension: EXT_paletted_texture

- optional extension: EXT_shared_texture_palette

• since year 2004, there is no graphics card supporting the above extensions

- old NVIDIA chips such as GeForce 5 series can support it.

- no ATI chips support it.

• Conclusively, new implementations are required



API Features


2.5 GL Errors



Geometric Primitives • All geometric primitives are specified by vertices


GL_TRIANGLE_STRIP

GL_TRIANGLE_FAN

GL_POINTS GL_LINES

GL_LINE_LOOP GL_LINE_STRIP

GL_TRIANGLES

GL_QUADS GL_QUAD_STRIP

GL_POLYGON


2.6 Begin/End Paradigm • drawing primitives:

- points

- line segment, line strip, line loop

- triangle, triangle strip, triangle fan



2.6 Begin/End Paradigm • state machine approach

• not supported in OpenGL ES

• glBegin( GL_TRIANGLES );

- glColor4f( 1.0F, 0.5F, 0.5F, 1.0F );

- glVertex2f( 0.0F, 0.0F );



• glEnd( );



2.7 Vertex Specification • float version only



2.8 Vertex Arrays • float version only

• no stride : always tightly packed arrays



2.8 Vertex Arrays • DrawArrays, DrawElements : similar to OpenGL ES



2.10 Coordinate Transformations • corresponds to OpenGL ES 1.1 features



2.10 Coordinate Transformations • no texture matrix



2.13 Colors and Coloring • single material properties for front and back faces



2.13 Colors and Coloring • only 2 lights

• no spot light



2.13 Colors and Coloring • no two side lighting

• color material support



3.2 Antialiasing • no multisampling support



3.3 Points •minimum requirement: only for point size = 1



3.4 Line Segments • line stipples are supported



3.5 Polygons • polygon stipples are also support



3.8 Texturing • supported image types: unsigned byte only



3.8 Texturing • texture image formats and types



3.8 Texturing • 2D texture only



3.8 Texturing • no texture release !

- no garbage collection

- i.e., only memory allocations



3.8 Texturing • texture environment support

- limited environment modes: MODULATE, REPLACE, DECAL, BLEND, ADD



3.9 Fog

• no fog support



Getting to the Framebuffer


Blending Depth

Test Dithering Logical

Operations

Scissor

Test

Stencil

Test

Alpha

Test

Fra

gm

ent

Fra

meb

uff

er


Scissor Box, Alpha Test • Additional Clipping Test

glScissor( x, y, w, h )

- any fragments outside of box are clipped

- useful for updating a small section of a viewport

• Reject pixels based on their alpha value glAlphaFunc( func, value )

glEnable( GL_ALPHA_TEST )

- use alpha as a mask in textures



Stencil Buffer glStencilFunc( func, ref, mask )

glStencilOp( fail, zfail, zpass )

• controlled drawing based on values in the stencil buffer

- Example: create a mask in stencil buffer

and draw only objects not in mask area


stencil area

for the mirror


Blending • Combine pixels with what’s in already

in the framebuffer glBlendFunc( src, dst )


Framebuffer

Pixel (dst)

Blending

Equation Fragment

(src)

Blended

Pixel

pfr CdstCsrcC


4.1 Per-Fragment Operations • restricted alpha functions: LEQUAL, ALWAYS only



4.1 Per-Fragment Operations • restricted depth function support: LESS, LEQUAL, ALWAYS only



4.1 Per-Fragment Operations • Blend Factor Combinations

• no other modes are supported



4.1 Per-Fragment Operations • restricted blend function support



4.2 Whole Frame-buffer Operations • same to OpenGL ES



2.12 Current Raster Position • specify the location for glBitmap, glDrawPixels, glCopyPixels



3.6 Pixel Rectangles / 3.7 Bitmaps • DrawPixels : RGBA image only

• Bitmap : B/W image, drawn with current raster color

- current raster color = current color when the last glRasterPos( ) called.



4.3 Pixels • ReadPixels : RGBA, unsigned byte only

• CopyPixels : specified region current raster position



5.4 Display Lists

• no release of allocated lists



5.5 Flush and Finish



5.6 Hints • only hints, maybe not working



6.1 Querying • no double type support



Core Extension: OES_single_precision



Required: EXT_paletted_texture • paletted texture



Required: EXT_paletted_texture • COLOR_INDEX8 are supported



Required: EXT_paletted_texture • add new functions



Optional: EXT_shared_texture_palette • affected functions:



Closing Remarks

65 mobile graphics lab@KNU


Summary

• OpenGL SC : safety critical profile

- based on OpenGL 1.3

- similar to OpenGL ES 1.1

- but, some distinguished features - begin-end paradigm

- display lists

- texture palettes

• future works

- a new version is expected

- conformance test passed implementations are expected to be used widely

OpenGL SC

Technology

Transcript of OpenGL SC