Merge pull request #25033 from sarbes/font-shader-clipping-gles

GLES: Add font shader clipping

1 files changed, 39 insertions, 0 deletions

diff --git a/system/shaders/GLES/2.0/gles_shader_clip.vert b/system/shaders/GLES/2.0/gles_shader_clip.vert
new file mode 100644
index 0000000000..513a24456c
--- /dev/null
+++ b/system/shaders/GLES/2.0/gles_shader_clip.vert
@@ -0,0 +1,39 @@
+/*
+ *  Copyright (C) 2024 Team Kodi
+ *  This file is part of Kodi - https://kodi.tv
+ *
+ *  SPDX-License-Identifier: GPL-2.0-or-later
+ *  See LICENSES/README.md for more information.
+ */
+
+#version 100
+
+attribute vec4 m_attrpos;
+attribute vec4 m_attrcol;
+attribute vec4 m_attrcord0;
+attribute vec4 m_attrcord1;
+varying vec4 m_cord0;
+varying vec4 m_cord1;
+varying vec4 m_colour;
+uniform mat4 m_matrix;
+uniform vec4 m_shaderClip;
+uniform vec4 m_cordStep;
+
+// this shader can be used in cases where clipping via glScissor() is not
+// possible (e.g. when rotating). it can't discard triangles, but it may 
+// degenerate them.
+
+void main()
+{
+  // limit the vertices to the clipping area
+  vec4 position = m_attrpos;
+  position.xy = clamp(position.xy, m_shaderClip.xy, m_shaderClip.zw);
+  gl_Position = m_matrix * position;
+
+  // correct texture coordinates for clipped vertices
+  vec2 clipDist = m_attrpos.xy - position.xy;
+  m_cord0.xy = m_attrcord0.xy - clipDist * m_cordStep.xy;
+  m_cord1.xy = m_attrcord1.xy - clipDist * m_cordStep.zw;
+
+  m_colour = m_attrcol;
+}