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IDProjectCategoryView StatusDate SubmittedLast Update
0032238Open CASCADE[OCCT] OCCT:Visualizationpublic2021-03-22 20:422021-08-24 14:51
Reporterkgv 
Assigned Tokgv 
PrioritynormalSeverityminor 
StatusnewResolutionopen 
PlatformOSOS Version
Product Version[OCCT] 7.5.0 
Target Version[OCCT] 7.7.0Fixed in Version 
Summary0032238: Visualization, TKOpenGl - GLSL compilation errors when using ANGLE (OpenGL ES 2.0) with disabled highp
DescriptionDisabling OpenGl_Context::hasHighp leads to the following errors:
TKOpenGl | Type: Error | ID: 0 | Severity: High | Message:
  Failed to link program object [occt_unlit0000]! Linker log:
Precisions for uniform 'occWorldViewMatrix' differ between vertex and fragment shaders

The reason is that Declarations.glsl declares matrix uniforms for both Vertex and Fragment shaders. And when highp is unsupported by hardware (very old OpenGL ES 2.0), the precision qualifiers of the same uniform become different.

In practice, the uniform is used only within vertex shader, so that Android hardware tolerated such syntax - unused uniform variables have been removed from Fragment shader before validation.
Issue happened only within Phong GLSL program, which has done matrix calculations in Framment shader until 0032042.
ANGLE library is, however, more strict about GLSL syntax and explicitly rejects such shaders.
Steps To Reproduce
pload MODELING VISUALIZATION
vdriver -load GLES
vcaps -maxVersion 2 0
# there is no such flag yet
#vcaps -highp 0
vinit View1
TagsNo tags attached.
Test case number
Attached Files

- Relationships
related to 0032042verifiedbugmaster Visualization, TKOpenGl - pre-multiply headlight flag into light source position 

-  Notes
There are no notes attached to this issue.

- Issue History
Date Modified Username Field Change
2021-03-22 20:42 kgv New Issue
2021-03-22 20:42 kgv Assigned To => kgv
2021-03-22 20:42 kgv Relationship added related to 0032042
2021-03-22 20:43 kgv Summary Visualization, TKOpenGl - GLSL compilation errors when using ANGLE (OpenGL ES 2.0) with disable highp => Visualization, TKOpenGl - GLSL compilation errors when using ANGLE (OpenGL ES 2.0) with disabled highp
2021-03-22 20:45 kgv Steps to Reproduce Updated View Revisions
2021-08-24 14:51 kgv Target Version 7.6.0* => 7.7.0


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