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https://github.com/KhronosGroup/glslang
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9220dbb078
Reimplement the whole workflow to make that: precise'ness of struct
members won't spread to other non-precise members of the same struct
instance.
Approach:
1. Build the map from symbols to their defining nodes. And for each
object node (StructIndex, DirectIndex, Symbol nodes, etc), generates an
accesschain path. Different AST nodes that indicating a same object
should have the same accesschain path.
2. Along the building phase in step 1, collect the initial set of
'precise' (AST qualifier: 'noContraction') objects' accesschain paths.
3. Start with the initial set of 'precise' accesschain paths, use it as
a worklist, do as the following steps until the worklist is empty:
1) Pop an accesschain path from worklist.
2) Get the symbol part from the accesschain path.
3) Find the defining nodes of that symbol.
4) For each defining node, check whether it is defining a 'precise'
object, or its assignee has nested 'precise' object. Get the
incremental path from assignee to its nested 'precise' object (if
any).
5) Traverse the right side of the defining node, obtain the
accesschain paths of the corresponding involved 'precise' objects.
Update the worklist with those new objects' accesschain paths.
Label involved operations with 'noContraction'.
In each step, whenever we find the parent object of an nested object is
'precise' (has 'noContraction' qualifier), we let the nested object
inherit the 'precise'ness from its parent object.
37 lines
1.0 KiB
GLSL
37 lines
1.0 KiB
GLSL
#version 310 es
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#extension GL_EXT_tessellation_shader : require
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#extension GL_EXT_gpu_shader5 : require
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layout(triangles, equal_spacing) in;
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layout(location = 0) in highp vec2 in_te_position[];
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layout(location = 0) out mediump vec4 in_f_color;
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precise gl_Position;
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void main(void) {
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highp vec2 pos = gl_TessCoord.x * in_te_position[0] +
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gl_TessCoord.y * in_te_position[1] +
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gl_TessCoord.z * in_te_position[2];
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highp float f =
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sqrt(3.0 * min(gl_TessCoord.x, min(gl_TessCoord.y, gl_TessCoord.z))) *
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0.5 +
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0.5;
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in_f_color = vec4(gl_TessCoord * f, 1.0);
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// Offset the position slightly, based on the parity of the bits in the float
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// representation.
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// This is done to detect possible small differences in edge vertex positions
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// between patches.
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uvec2 bits = floatBitsToUint(pos);
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uint numBits = 0u;
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for (uint i = 0u; i < 32u; i++)
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numBits +=
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((bits[0] << i) & 1u) + ((bits[1] << i) & 1u);
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pos += float(numBits & 1u) * 0.04;
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gl_Position = vec4(pos, 0.0, 1.0);
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}
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