https://bugs.kde.org/show_bug.cgi?id=482514
Bug ID: 482514
Summary: Gradient start and stop does not evenly gradient
across all channels when alpha is involved
Classification: Applications
Product: krita
Version: 5.2.1
Platform: Compiled Sources
OS: All
Status: REPORTED
Severity: normal
Priority: NOR
Component: Brush engines
Assignee: krita-bugs-n...@kde.org
Reporter: madmr...@outlook.com
Target Milestone: ---
SUMMARY
In the game engine that I contribute images to, the way light sources render
through objects relies on the alpha channel as well as the RGB values to
determine strength of the light. I'm using Krita to author my images but other
people are using PS and GIMP which does not have this issue.
The issue is that a gradient start and stop going from a solid color to a fully
transparent value is ONLY doing a gradient on alpha values, it isn't affecting
the RGB values. This is wrong in that the value of a gradient is more than
alpha value.
STEPS TO REPRODUCE
1. New Image (RGB/Alpha 8 bit)
2. New Gradient Fill. Use custom colors for the start and end stops
3. Stop 1 should be ARGB 167, 167, 167, 167 (or #a7a7a7 with alpha value of
65.49%)
4. Stop 2 should be ARGB 0, 0, 0, 0 (#000000 with alpha value of 0%)
5. Using Gradient brush radial gradient, draw a large enough spot from center
of canvas out (about the size of a tennis ball)
6. Using the color sampler tool, sample the gradient from center outwards (make
sure you can see the color sampler tool output with the channel values all
listed)
OBSERVED RESULT
Only the Alpha value is being changed in the gradient, even though I specified
going from "grey" to "black" as well
EXPECTED RESULT
Like PS and GIMP I would expect an even distribution of all channels + Alpha
going from 167 to 0. This makes it impossible for me to easily create images
for this game engine which needs all channel information to correctly be used.
In addition, the gradient itself is just not the same.
Krita
Version: 5.2.1
Installation type: installer / portable package
Hidpi: true
Qt
Version (compiled): 5.15.7
Version (loaded): 5.15.7
OS Information
Build ABI: x86_64-little_endian-llp64
Build CPU: x86_64
CPU: x86_64
Kernel Type: winnt
Kernel Version: 10.0.23258
Pretty Productname: Windows 10 Version 2009
Product Type: windows
Product Version: 10
Locale
Languages: en_US, en, en_Latn_US
C locale: C
QLocale current: en
QLocale system: en
QTextCodec for locale: UTF-8
Process ACP: 65001 (UTF-8)
System locale default ACP: 1252 (ANSI - Latin I)
OpenGL Info
Vendor: "Google Inc. (Intel)"
Renderer: "ANGLE (Intel, Intel(R) Iris(R) Xe Graphics Direct3D11 vs_5_0
ps_5_0, D3D11-31.0.101.4502)"
Driver version: "OpenGL ES 3.0.0 (ANGLE 2.1.0 git hash:
f2280c0c5f93+krita_qt5)"
Shading language: "OpenGL ES GLSL ES 3.00 (ANGLE 2.1.0 git hash:
f2280c0c5f93+krita_qt5)"
Requested format: QSurfaceFormat(version 3.0, options
QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize 8,
greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8,
samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0,
colorSpace QSurfaceFormat::DefaultColorSpace, profile
QSurfaceFormat::NoProfile)
Current format: QSurfaceFormat(version 3.0, options
QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize 8,
greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8,
samples 0, swapBehavior QSurfaceFormat::DefaultSwapBehavior, swapInterval 0,
colorSpace QSurfaceFormat::DefaultColorSpace, profile
QSurfaceFormat::NoProfile)
GL version: 3.0
Supports deprecated functions false
Is OpenGL ES: true
supportsBufferMapping: true
supportsBufferInvalidation: false
forceDisableTextureBuffers: true
Extensions:
GL_ANGLE_base_vertex_base_instance
GL_ANGLE_get_serialized_context_string
GL_OES_draw_elements_base_vertex
GL_ANGLE_texture_multisample
GL_EXT_texture_compression_dxt1
GL_OES_compressed_EAC_RG11_signed_texture
GL_ANGLE_texture_usage
GL_EXT_shader_texture_lod
GL_EXT_sRGB
GL_KHR_parallel_shader_compile
GL_OES_texture_float_linear
GL_EXT_color_buffer_float
GL_CHROMIUM_bind_generates_resource
GL_EXT_color_buffer_half_float
GL_OES_texture_stencil8
GL_ANGLE_texture_compression_dxt5
GL_KHR_debug
GL_OES_vertex_array_object
GL_OES_EGL_image_external
GL_ANGLE_lossy_etc_decode
GL_WEBGL_video_texture
GL_ANGLE_memory_size
GL_EXT_blend_func_extended
GL_OES_compressed_EAC_RG11_unsigned_texture
GL_ANGLE_depth_texture
GL_EXT_disjoint_timer_query
GL_OES_depth24
GL_CHROMIUM_sync_query
GL_ANGLE_copy_texture_3d
GL_EXT_map_buffer_range
GL_ANGLE_pack_reverse_row_order
GL_OES_fbo_render_mipmap
GL_EXT_texture_type_2_10_10_10_REV
GL_OES_rgb8_rgba8
GL_OES_depth32
GL_ANGLE_framebuffer_blit
GL_EXT_frag_depth
GL_OES_compressed_ETC2_sRGB8_alpha8_texture
GL_EXT_draw_buffers_indexed
GL_EXT_texture_compression_s3tc_srgb
GL_CHROMIUM_copy_compressed_texture
GL_EXT_texture_filter_anisotropic
GL_ANGLE_robust_client_memory
GL_ANGLE_multi_draw
GL_OES_compressed_ETC2_RGB8_texture
GL_OES_draw_buffers_indexed
GL_NV_pixel_buffer_object
GL_ANGLE_program_cache_control
GL_EXT_texture_compression_bptc
GL_ANGLE_instanced_arrays
GL_ANGLE_request_extension
GL_EXT_EGL_image_external_wrap_modes
GL_ANGLE_client_arrays
GL_OES_surfaceless_context
GL_EXT_texture_format_BGRA8888
GL_EXT_texture_compression_rgtc
GL_EXT_texture_rg
GL_EXT_multi_draw_indirect
GL_EXT_discard_framebuffer
GL_EXT_draw_buffers
GL_OES_get_program_binary
GL_OES_texture_border_clamp
GL_NV_fence
GL_OVR_multiview2
GL_OES_compressed_EAC_R11_signed_texture
GL_OES_element_index_uint
GL_OES_compressed_EAC_R11_unsigned_texture
GL_OES_EGL_image_external_essl3
GL_ANGLE_multiview_multisample
GL_EXT_texture_storage
GL_CHROMIUM_lose_context
GL_OES_mapbuffer
GL_OES_texture_half_float_linear
GL_EXT_instanced_arrays
GL_EXT_read_format_bgra
GL_OES_texture_npot
GL_OES_compressed_ETC2_punchthroughA_RGBA8_texture
GL_CHROMIUM_bind_uniform_location
GL_EXT_draw_elements_base_vertex
GL_ANGLE_provoking_vertex
GL_ANGLE_translated_shader_source
GL_EXT_float_blend
GL_EXT_clip_control
GL_EXT_unpack_subimage
GL_EXT_robustness
GL_OES_EGL_image
GL_ANGLE_texture_compression_dxt3
GL_EXT_debug_label
GL_EXT_texture_norm16
GL_NV_EGL_stream_consumer_external
GL_OVR_multiview
GL_AMD_performance_monitor
GL_OES_compressed_ETC2_RGBA8_texture
GL_EXT_multisampled_render_to_texture
GL_ANGLE_framebuffer_multisample
GL_NV_framebuffer_blit
GL_ANGLE_get_tex_level_parameter
GL_OES_texture_half_float
GL_OES_compressed_ETC2_sRGB8_texture
GL_EXT_blend_minmax
GL_OES_standard_derivatives
GL_OES_packed_depth_stencil
GL_NV_pack_subimage
GL_OES_texture_float
GL_EXT_occlusion_query_boolean
GL_ANGLE_base_vertex_base_instance_shader_builtin
GL_CHROMIUM_copy_texture
GL_EXT_debug_marker
GL_OES_compressed_ETC2_punchthroughA_sRGB8_alpha_texture
QPA OpenGL Detection Info
supportsDesktopGL: true
supportsAngleD3D11: true
isQtPreferAngle: true
Detected renderers:
(Supported) ANGLE (Microsoft, Microsoft Basic Render Driver Direct3D11
vs_5_0 ps_5_0, D3D11-10.0.23258.1000) (OpenGL ES 3.0.0 (ANGLE 2.1.0 git hash:
f2280c0c5f93+krita_qt5))
(Supported) ANGLE (Intel, Intel(R) Iris(R) Xe Graphics Direct3D11 vs_5_0
ps_5_0, D3D11-31.0.101.4502) (OpenGL ES 3.0.0 (ANGLE 2.1.0 git hash:
f2280c0c5f93+krita_qt5))
(Supported) Intel(R) Iris(R) Xe Graphics (3.3.0 - Build 31.0.101.4502)
useBufferInvalidation (config option): false
Hardware Information
GPU Acceleration: auto
Memory: 16208 Mb
Number of Cores: 12
Swap Location: C:/Users/markri/AppData/Local/Temp
Built for: sse2
Base instruction set: fma3+avx2
Supported instruction sets: fma3+avx2 avx2 fma3+avx avx fma4 fma3+sse4.2
sse4.2 sse4.1 ssse3 sse3 sse2
Current Settings
Current Swap Location: C:/Users/markri/AppData/Local/Temp
Current Swap Location writable: true
Undo Enabled: true
Undo Stack Limit: 200
Use OpenGL: true
Use OpenGL Texture Buffer: true
Disable Vector Optimizations: false
Disable AVX Optimizations: false
Canvas State: OPENGL_SUCCESS
Autosave Interval: 420
Use Backup Files: true
Number of Backups Kept: 2
Backup File Suffix: ~
Backup Location: C:/Users/markri/AppData/Local/Temp
Backup Location writable: true
Resource Location: C:/Users/markri/AppData/Roaming/krita
Use Win8 Pointer Input: true
Use RightMiddleTabletButton Workaround: false
Levels of Detail Enabled: false
Use Zip64: false
Loaded Python Plugins
colorspace
comics_project_management_tools
documenttools
exportlayers
filtermanager
lastdocumentsdocker
plugin_importer
quick_settings_docker
scripter
tenbrushes
tenscripts
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