From 7ad802cf3ae500bc72863b6dba0f28a488fce3d1 Mon Sep 17 00:00:00 2001 From: Brecht Van Lommel Date: Tue, 23 Apr 2019 13:56:30 +0200 Subject: Cycles/Eevee: unified and improved texture image color space handling Cycles now uses the color space on the image datablock, and uses OpenColorIO to convert to scene linear as needed. Byte images do not take extra memory, they are compressed in scene linear + sRGB transfer function which in common cases is a no-op. Eevee and workbench were changed to work similar. Float images are stored as scene linear. Byte images are compressed as scene linear + sRGB and stored in a GL_SRGB8_ALPHA8 texture. From the GLSL shader side this means they are read as scene linear, simplifying the code and taking advantage of hardware support. Further, OpenGL image textures are now all stored with premultiplied alpha. Eevee texture sampling looks a little different now because interpolation happens premultiplied and in scene linear space. Overlays and grease pencil work in sRGB space so those now have an extra conversion to sRGB after reading from image textures. This is not particularly elegant but as long as engines use different conventions, one or the other needs to do conversion. This change breaks compatibility for cases where multiple image texture nodes were using the same image with different color space node settings. However it gives more predictable behavior for baking and texture painting if save, load and image editing operations have a single color space to handle. Differential Revision: https://developer.blender.org/D4807 --- .../workbench/shaders/workbench_common_lib.glsl | 30 ++++++---------------- 1 file changed, 8 insertions(+), 22 deletions(-) (limited to 'source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl') diff --git a/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl b/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl index c76ad8c1d7b..96f8f6e4c7a 100644 --- a/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl +++ b/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl @@ -140,32 +140,18 @@ vec2 matcap_uv_compute(vec3 I, vec3 N, bool flipped) return matcap_uv * 0.496 + 0.5; } -float srgb_to_linearrgb(float c) -{ - if (c < 0.04045) { - return (c < 0.0) ? 0.0 : c * (1.0 / 12.92); - } - else { - return pow((c + 0.055) * (1.0 / 1.055), 2.4); - } -} - -vec4 srgb_to_linearrgb(vec4 col_from) -{ - vec4 col_to; - col_to.r = srgb_to_linearrgb(col_from.r); - col_to.g = srgb_to_linearrgb(col_from.g); - col_to.b = srgb_to_linearrgb(col_from.b); - col_to.a = col_from.a; - return col_to; -} - -vec4 workbench_sample_texture(sampler2D image, vec2 coord, bool srgb, bool nearest_sampling) +vec4 workbench_sample_texture(sampler2D image, vec2 coord, bool nearest_sampling) { vec2 tex_size = vec2(textureSize(image, 0).xy); /* TODO(fclem) We could do the same with sampler objects. * But this is a quick workaround instead of messing with the GPUTexture itself. */ vec2 uv = nearest_sampling ? (floor(coord * tex_size) + 0.5) / tex_size : coord; vec4 color = texture(image, uv); - return (srgb) ? srgb_to_linearrgb(color) : color; + + /* Unpremultiply, ideally shaders would be added so this is not needed. */ + if (!(color.a == 0.0 || color.a == 1.0)) { + color.rgb = color.rgb / color.a; + } + + return color; } -- cgit v1.2.3