From c5de5ae479df3956c5d6f8a9eda2e5d6790e3e98 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Thu, 26 Jun 2014 10:45:20 -0400
Subject: [PATCH] rework text shader, add basic and rect shaders

---
 runtime/shaders/basic.f.glsl |  6 ++++++
 runtime/shaders/basic.v.glsl | 21 +++++++++++++++++++++
 runtime/shaders/rect.v.glsl  | 23 +++++++++++++++++++++++
 runtime/shaders/text.f.glsl  |  2 ++
 runtime/shaders/text.v.glsl  | 23 ++++++++++++++++-------
 5 files changed, 68 insertions(+), 7 deletions(-)
 create mode 100644 runtime/shaders/basic.f.glsl
 create mode 100644 runtime/shaders/basic.v.glsl
 create mode 100644 runtime/shaders/rect.v.glsl

diff --git a/runtime/shaders/basic.f.glsl b/runtime/shaders/basic.f.glsl
new file mode 100644
index 0000000..b51cfff
--- /dev/null
+++ b/runtime/shaders/basic.f.glsl
@@ -0,0 +1,6 @@
+uniform vec4 color;
+
+void main(void)
+{
+    gl_FragColor = color;
+}
diff --git a/runtime/shaders/basic.v.glsl b/runtime/shaders/basic.v.glsl
new file mode 100644
index 0000000..a281dd3
--- /dev/null
+++ b/runtime/shaders/basic.v.glsl
@@ -0,0 +1,21 @@
+/* Viewport width and height */
+uniform ivec2 viewport_size;
+/* Position of lower left corner of glyph */
+uniform ivec2 position;
+
+/* Vertex coordinates: x, y */
+attribute vec2 coords;
+
+/**
+ * Map coordinates such that:
+ * (0 .. viewport_size.[xy]) => (-1.0 .. 1.0)
+ */
+vec2 map_to_screen(vec2 position)
+{
+    return 2.0 * position / viewport_size - 1.0;
+}
+
+void main(void)
+{
+    gl_Position = vec4(map_to_screen((vec2)position + coords), 0, 1);
+}
diff --git a/runtime/shaders/rect.v.glsl b/runtime/shaders/rect.v.glsl
new file mode 100644
index 0000000..2c551b1
--- /dev/null
+++ b/runtime/shaders/rect.v.glsl
@@ -0,0 +1,23 @@
+/* Viewport width and height */
+uniform ivec2 viewport_size;
+/* Position of lower left corner of rectangle */
+uniform ivec2 position;
+/* Size of the rectangle */
+uniform ivec2 size;
+
+/* Vertex coordinates: x, y (0 or 1) */
+attribute ivec2 coords;
+
+/**
+ * Map coordinates such that:
+ * (0 .. viewport_size.[xy]) => (-1.0 .. 1.0)
+ */
+vec2 map_to_screen(vec2 position)
+{
+    return 2.0 * position / viewport_size - 1.0;
+}
+
+void main(void)
+{
+    gl_Position = vec4(map_to_screen((vec2)(position + coords * size)), 0, 1);
+}
diff --git a/runtime/shaders/text.f.glsl b/runtime/shaders/text.f.glsl
index 3cdfc99..0494621 100644
--- a/runtime/shaders/text.f.glsl
+++ b/runtime/shaders/text.f.glsl
@@ -1,5 +1,7 @@
+/* Texture coordinate: s, t */
 varying vec2 texture_coord_v;
 
+/* Texture unit */
 uniform sampler2D texture;
 uniform vec4 color;
 
diff --git a/runtime/shaders/text.v.glsl b/runtime/shaders/text.v.glsl
index c0501dc..5851094 100644
--- a/runtime/shaders/text.v.glsl
+++ b/runtime/shaders/text.v.glsl
@@ -1,16 +1,25 @@
-uniform vec2 screen_size;
-uniform vec2 position;
+/* Viewport width and height */
+uniform ivec2 viewport_size;
+/* Position of lower left corner of glyph */
+uniform ivec2 position;
 
+/* Vertex coordinates: x, y, s, t */
 attribute vec4 coords;
 
+/* Output texture coordinate: s, t */
 varying vec2 texture_coord_v;
 
+/**
+ * Map coordinates such that:
+ * (0 .. viewport_size.[xy]) => (-1.0 .. 1.0)
+ */
+vec2 map_to_screen(vec2 position)
+{
+    return 2.0 * position / viewport_size - 1.0;
+}
+
 void main(void)
 {
-    // Map coordinates such that:
-    // (0 .. screen_size.x) => (-1.0 .. 1.0)
-    gl_Position = vec4(2.0 * (position.x + coords.x) / screen_size.x - 1.0,
-                       2.0 * (position.y + coords.y) / screen_size.y - 1.0,
-                       0, 1);
+    gl_Position = vec4(map_to_screen((vec2)position + coords.xy), 0, 1);
     texture_coord_v = coords.zw;
 }