Files
gio/gpu/shaders/stencil.vert
T
Viktor 24951a7ee7 gpu, op, internal/ops: add affine transformations
Add support for affine transformations. The key changes are outlined
below.

- Painting/clipping with rectangles is handled by, for complex
  transforms, creating clipping paths representing the transformed
  rectangle and using a larger bounding box. Cover/Blit shaders updated
  correspondingly to correctly map texture cordinates from the new
  bounding boxes.
- Since path splitting must happen on CPU the transforms must happen CPU
  side as well - offsets removed from shaders.
- Complex transforms will lead to different path splitting which means
  that GPU arrays can no longer be cached if the transform has changed.
  Thus the current transform is added as a key to the cache.
- Add a public API to op for setting Affine transformations.

There are a number of optimizations that could be explored further but
which are left out now:
- Caching also of CPU operations (e.g path splitting & transforms) and
  not only caching the GPU arrays.
- Allow for re-use of cached GPU vertices if the transformation change
  is a pure offset / scaling since the splitting is then the same.

Signed-off-by: Viktor <viktor.ogeman@gmail.com>
2020-06-21 11:17:53 +02:00

53 lines
1.1 KiB
GLSL

#version 310 es
// SPDX-License-Identifier: Unlicense OR MIT
precision highp float;
layout(binding = 0) uniform Block {
vec4 transform;
};
layout(location=0) in float corner;
layout(location=1) in float maxy;
layout(location=2) in vec2 from;
layout(location=3) in vec2 ctrl;
layout(location=4) in vec2 to;
layout(location=0) out vec2 vFrom;
layout(location=1) out vec2 vCtrl;
layout(location=2) out vec2 vTo;
void main() {
// Add a one pixel overlap so curve quads cover their
// entire curves. Could use conservative rasterization
// if available.
vec2 from = from;
vec2 ctrl = ctrl;
vec2 to = to;
float maxy = maxy;
vec2 pos;
float c = corner;
if (c >= 0.375) {
// North.
c -= 0.5;
pos.y = maxy + 1.0;
} else {
// South.
pos.y = min(min(from.y, ctrl.y), to.y) - 1.0;
}
if (c >= 0.125) {
// East.
pos.x = max(max(from.x, ctrl.x), to.x)+1.0;
} else {
// West.
pos.x = min(min(from.x, ctrl.x), to.x)-1.0;
}
vFrom = from-pos;
vCtrl = ctrl-pos;
vTo = to-pos;
pos = pos*transform.xy + transform.zw;
gl_Position = vec4(pos, 1, 1);
}