Make demo programs work from any directory, and install them

4 files changed, 78 insertions, 0 deletions

diff --git a/examples/shaders/header_330.glsl b/examples/shaders/header_330.glsl
new file mode 100644
index 0000000..bfe7a00
--- /dev/null
+++ b/examples/shaders/header_330.glsl
@@ -0,0 +1,5 @@
+#version 330 core
+
+#define INTER(qualifiers)
+#define UBO(qualifiers) layout(std140)
+
diff --git a/examples/shaders/header_420.glsl b/examples/shaders/header_420.glsl
new file mode 100644
index 0000000..55fbe8a
--- /dev/null
+++ b/examples/shaders/header_420.glsl
@@ -0,0 +1,5 @@
+#version 420 core
+
+#define INTER(qualifiers) layout(qualifiers)
+#define UBO(qualifiers) layout(std140, qualifiers)
+
diff --git a/examples/shaders/rect.frag b/examples/shaders/rect.frag
new file mode 100644
index 0000000..ecec50d
--- /dev/null
+++ b/examples/shaders/rect.frag
@@ -0,0 +1,33 @@
+/* The fragment shader uses the UV coordinates to calculate whether it is in
+   the T, R, B, or L border.  These are then mixed with the border color, and
+   their inverse is mixed with the fill color, to calculate the fragment color.
+   For example, if we are in the top border, then T=1, so the border mix factor
+   TRBL=1, and the fill mix factor (1-TRBL) is 0.
+
+   The use of pixel units here is handy because the border width can be
+   specified precisely in pixels to draw sharp lines.  The border width is just
+   hardcoded, but could be made a uniform or vertex attribute easily enough. */
+
+INTER(location = 0) noperspective in vec2 f_uv;
+INTER(location = 1) noperspective in vec2 f_size;
+INTER(location = 2) noperspective in vec4 f_fillColor;
+
+layout(location = 0) out vec4 FragColor;
+
+void
+main()
+{
+	const float borderWidth = 2.0;
+
+	vec4  borderColor = f_fillColor + vec4(0.0, 0.4, 0.4, 0.0);
+	float t           = step(borderWidth, f_uv[1]);
+	float r           = step(borderWidth, f_size.x - f_uv[0]);
+	float b           = step(borderWidth, f_size.y - f_uv[1]);
+	float l           = step(borderWidth, f_uv[0]);
+	float fillMix     = t * r * b * l;
+	float borderMix   = 1.0 - fillMix;
+	vec4  fill        = fillMix * f_fillColor;
+	vec4  border      = borderMix * borderColor;
+
+	FragColor = fill + border;
+}
diff --git a/examples/shaders/rect.vert b/examples/shaders/rect.vert
new file mode 100644
index 0000000..09f1917
--- /dev/null
+++ b/examples/shaders/rect.vert
@@ -0,0 +1,35 @@
+/* The vertex shader is trivial, but forwards scaled UV coordinates (in pixels)
+   to the fragment shader for drawing the border. */
+
+UBO(binding = 0) uniform UniformBufferObject
+{
+	mat4 projection;
+} ubo;
+
+layout(location = 0) in vec2 v_position;
+layout(location = 1) in vec2 v_origin;
+layout(location = 2) in vec2 v_size;
+layout(location = 3) in vec4 v_fillColor;
+
+INTER(location = 0) noperspective out vec2 f_uv;
+INTER(location = 1) noperspective out vec2 f_size;
+INTER(location = 2) noperspective out vec4 f_fillColor;
+
+void
+main()
+{
+	// clang-format off
+	mat4 m = mat4(v_size[0],   0.0,         0.0, 0.0,
+	              0.0,         v_size[1],   0.0, 0.0,
+	              0.0,         0.0,         1.0, 0.0,
+	              v_origin[0], v_origin[1], 0.0, 1.0);
+	// clang-format on
+
+	mat4 MVP = ubo.projection * m;
+
+	f_uv        = v_position * v_size;
+	f_size      = v_size;
+	f_fillColor = v_fillColor;
+
+	gl_Position = MVP * vec4(v_position, 0.0, 1.0);
+}