From 6c268e0f98722c3253366b639a3a0abe37c8835d Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 12 Dec 2021 16:12:01 +0000
Subject: Introduce the UI shader

---
 gfx/gl/shader.cpp          |  1 -
 gfx/gl/shaders/uiShader.fs | 11 +++++++++++
 gfx/gl/shaders/uiShader.vs | 13 +++++++++++++
 gfx/gl/uiShader.cpp        | 14 ++++++++++++++
 gfx/gl/uiShader.h          | 18 ++++++++++++++++++
 5 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 gfx/gl/shaders/uiShader.fs
 create mode 100644 gfx/gl/shaders/uiShader.vs
 create mode 100644 gfx/gl/uiShader.cpp
 create mode 100644 gfx/gl/uiShader.h

diff --git a/gfx/gl/shader.cpp b/gfx/gl/shader.cpp
index 47e08c5..03e7899 100644
--- a/gfx/gl/shader.cpp
+++ b/gfx/gl/shader.cpp
@@ -76,4 +76,3 @@ Shader::setModel(const Location & loc, Program pid) const
 		glUniformMatrix4fv(prog.model_uniform, 1, GL_FALSE, glm::value_ptr(model));
 	}
 }
-
diff --git a/gfx/gl/shaders/uiShader.fs b/gfx/gl/shaders/uiShader.fs
new file mode 100644
index 0000000..907c4f1
--- /dev/null
+++ b/gfx/gl/shaders/uiShader.fs
@@ -0,0 +1,11 @@
+#version 130
+
+in vec2 texCoord0;
+
+uniform sampler2D sampler;
+
+void
+main()
+{
+	gl_FragColor = texture(sampler, texCoord0);
+}
diff --git a/gfx/gl/shaders/uiShader.vs b/gfx/gl/shaders/uiShader.vs
new file mode 100644
index 0000000..0d00fed
--- /dev/null
+++ b/gfx/gl/shaders/uiShader.vs
@@ -0,0 +1,13 @@
+#version 130
+
+in vec4 position;
+
+out vec2 texCoord0;
+uniform mat4 uiProjection;
+
+void
+main()
+{
+	gl_Position = uiProjection * vec4(position.xy, 0.0, 1.0);
+	texCoord0 = position.zw;
+}
diff --git a/gfx/gl/uiShader.cpp b/gfx/gl/uiShader.cpp
new file mode 100644
index 0000000..2fbb0d4
--- /dev/null
+++ b/gfx/gl/uiShader.cpp
@@ -0,0 +1,14 @@
+#include "uiShader.h"
+#include <gfx/gl/shaders/fs-uiShader.h>
+#include <gfx/gl/shaders/vs-uiShader.h>
+#include <glm/gtc/type_ptr.hpp>
+#include <glm/gtx/transform.hpp>
+
+UIShader::UIShader(size_t width, size_t height) : program {uiShader_vs.compile(), uiShader_fs.compile()}
+{
+	if (auto loc = glGetUniformLocation(program.m_program, "uiProjection"); loc >= 0) {
+		glUseProgram(program.m_program);
+		const auto uiProjection = glm::ortho<float>(0, static_cast<float>(width), 0, static_cast<float>(height));
+		glUniformMatrix4fv(loc, 1, GL_FALSE, glm::value_ptr(uiProjection));
+	}
+}
diff --git a/gfx/gl/uiShader.h b/gfx/gl/uiShader.h
new file mode 100644
index 0000000..ff0e96d
--- /dev/null
+++ b/gfx/gl/uiShader.h
@@ -0,0 +1,18 @@
+#ifndef UISHADER_H
+#define UISHADER_H
+
+#include "programHandle.h"
+#include <cstdint>
+
+class UIShader {
+public:
+	UIShader(std::size_t width, std::size_t height);
+
+private:
+	class UIProgramHandle : public ProgramHandleBase {
+		using ProgramHandleBase::ProgramHandleBase;
+	};
+	UIProgramHandle program;
+};
+
+#endif
-- 
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