[gtk: 1/3] gl: fix compilation errors for legacy context shaders

[Emmanuele Bassi <ebassi src gnome org>]

commit 05ca6bc189a952fde12eb3e2f25edde538a5552e
Author: Elias Aebi <eyelash users noreply github com>
Date:   Sat Jul 14 14:20:30 2018 +0200

    gl: fix compilation errors for legacy context shaders

 gsk/resources/glsl/gl_common.fs.glsl | 79 ++++++++++++++++++++++++++++++++++--
 gsk/resources/glsl/gl_common.vs.glsl |  3 +-
 2 files changed, 77 insertions(+), 5 deletions(-)
---
diff --git a/gsk/resources/glsl/gl_common.fs.glsl b/gsk/resources/glsl/gl_common.fs.glsl
index 2ed6c75d23..a0b32d11ef 100644
--- a/gsk/resources/glsl/gl_common.fs.glsl
+++ b/gsk/resources/glsl/gl_common.fs.glsl
@@ -1,11 +1,82 @@
-uniform mat4 uMVP;
-uniform sampler2D uSource;
-uniform sampler2D uMask;
-uniform float uAlpha;
+uniform sampler2D u_source;
+uniform sampler2D u_mask;
+uniform mat4 u_projection;
+uniform mat4 u_modelview;
+uniform float u_alpha;
 uniform int uBlendMode;
+uniform vec4 u_viewport;
 
 varying vec2 vUv;
 
+
+struct RoundedRect
+{
+  vec4 bounds;
+  vec4 corner_widths;
+  vec4 corner_heights;
+};
+
+float
+ellipsis_dist (vec2 p, vec2 radius)
+{
+  if (radius == vec2(0, 0))
+    return 0.0;
+
+  vec2 p0 = p / radius;
+  vec2 p1 = 2.0 * p0 / radius;
+
+  return (dot(p0, p0) - 1.0) / length (p1);
+}
+
+float
+ellipsis_coverage (vec2 point, vec2 center, vec2 radius)
+{
+  float d = ellipsis_dist (point - center, radius);
+  return clamp (0.5 - d, 0.0, 1.0);
+}
+
+float
+rounded_rect_coverage (RoundedRect r, vec2 p)
+{
+  if (p.x < r.bounds.x || p.y < r.bounds.y ||
+      p.x >= r.bounds.z || p.y >= r.bounds.w)
+    return 0.0;
+
+  vec2 rad_tl = vec2(r.corner_widths.x, r.corner_heights.x);
+  vec2 rad_tr = vec2(r.corner_widths.y, r.corner_heights.y);
+  vec2 rad_br = vec2(r.corner_widths.z, r.corner_heights.z);
+  vec2 rad_bl = vec2(r.corner_widths.w, r.corner_heights.w);
+
+  vec2 ref_tl = r.bounds.xy + vec2( r.corner_widths.x,  r.corner_heights.x);
+  vec2 ref_tr = r.bounds.zy + vec2(-r.corner_widths.y,  r.corner_heights.y);
+  vec2 ref_br = r.bounds.zw + vec2(-r.corner_widths.z, -r.corner_heights.z);
+  vec2 ref_bl = r.bounds.xw + vec2( r.corner_widths.w, -r.corner_heights.w);
+
+  float d_tl = ellipsis_coverage(p, ref_tl, rad_tl);
+  float d_tr = ellipsis_coverage(p, ref_tr, rad_tr);
+  float d_br = ellipsis_coverage(p, ref_br, rad_br);
+  float d_bl = ellipsis_coverage(p, ref_bl, rad_bl);
+
+  vec4 corner_coverages = 1.0 - vec4(d_tl, d_tr, d_br, d_bl);
+
+  bvec4 is_out = bvec4(p.x < ref_tl.x && p.y < ref_tl.y,
+                       p.x > ref_tr.x && p.y < ref_tr.y,
+                       p.x > ref_br.x && p.y > ref_br.y,
+                       p.x < ref_bl.x && p.y > ref_bl.y);
+
+  return 1.0 - dot(vec4(is_out), corner_coverages);
+}
+
+RoundedRect
+rounded_rect_shrink (RoundedRect r, vec4 amount)
+{
+  vec4 new_bounds = r.bounds + vec4(1.0,1.0,-1.0,-1.0) * amount.wxyz;
+  vec4 new_widths = max (r.corner_widths - amount.wyyw, 0.0);
+  vec4 new_heights = max (r.corner_heights - amount.xxzz, 0.0);
+
+  return RoundedRect (new_bounds, new_widths, new_heights);
+}
+
 vec4 Texture(sampler2D sampler, vec2 texCoords) {
   return texture2D(sampler, texCoords);
 }
diff --git a/gsk/resources/glsl/gl_common.vs.glsl b/gsk/resources/glsl/gl_common.vs.glsl
index 3db2e4dc07..8d52641d1f 100644
--- a/gsk/resources/glsl/gl_common.vs.glsl
+++ b/gsk/resources/glsl/gl_common.vs.glsl
@@ -1,4 +1,5 @@
-uniform mat4 uMVP;
+uniform mat4 u_projection;
+uniform mat4 u_modelview;
 
 attribute vec2 aPosition;
 attribute vec2 aUv;