From 02049aeaa8806ef5d23fbf050be7e341e2d5bbde Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Fri, 4 Jun 2021 16:56:49 +0400
Subject: [PATCH] Add FragmentGlobalOpacity shader part.

---
 ui/gl/gl_primitives.cpp | 42 +++++++++++++++++++++++++++++++++--------
 ui/gl/gl_primitives.h   | 22 +++++++++++++++++----
 ui/gl/gl_shader.cpp     | 11 +++++++++++
 ui/gl/gl_shader.h       |  1 +
 4 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/ui/gl/gl_primitives.cpp b/ui/gl/gl_primitives.cpp
index 036e4f3..599b9f9 100644
--- a/ui/gl/gl_primitives.cpp
+++ b/ui/gl/gl_primitives.cpp
@@ -15,7 +15,7 @@ namespace Ui::GL {
 
 static_assert(std::is_same_v<float, GLfloat>);
 
-void FillRectVertices(float *coords, Rect rect) {
+void FillRectTriangleVertices(float *coords, Rect rect) {
 	coords[0] = coords[10] = rect.left();
 	coords[1] = coords[11] = rect.top();
 	coords[2] = rect.right();
@@ -31,7 +31,6 @@ void FillTriangles(
 		gsl::span<const float> coords,
 		not_null<QOpenGLBuffer*> buffer,
 		not_null<QOpenGLShaderProgram*> program,
-		QSize viewportWithFactor,
 		const QColor &color,
 		Fn<void()> additional) {
 	Expects(coords.size() % 6 == 0);
@@ -42,8 +41,6 @@ void FillTriangles(
 	buffer->bind();
 	buffer->allocate(coords.data(), coords.size() * sizeof(GLfloat));
 
-	f.glUseProgram(program->programId());
-	program->setUniformValue("viewport", QSizeF(viewportWithFactor));
 	program->setUniformValue("s_color", Uniform(color));
 
 	GLint position = program->attributeLocation("position");
@@ -65,6 +62,32 @@ void FillTriangles(
 	f.glDisableVertexAttribArray(position);
 }
 
+void FillRectangle(
+		QOpenGLFunctions &f,
+		not_null<QOpenGLShaderProgram*> program,
+		int skipVertices,
+		const QColor &color) {
+	const auto shift = [&](int elements) {
+		return reinterpret_cast<const void*>(
+			(skipVertices * 4 + elements) * sizeof(GLfloat));
+	};
+	program->setUniformValue("s_color", Uniform(color));
+
+	GLint position = program->attributeLocation("position");
+	f.glVertexAttribPointer(
+		position,
+		2,
+		GL_FLOAT,
+		GL_FALSE,
+		2 * sizeof(GLfloat),
+		shift(0));
+	f.glEnableVertexAttribArray(position);
+
+	f.glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+	f.glDisableVertexAttribArray(position);
+}
+
 void FillTexturedRectangle(
 		QOpenGLFunctions &f,
 		not_null<QOpenGLShaderProgram*> program,
@@ -120,8 +143,8 @@ void BackgroundFiller::fill(
 		const QRegion &region,
 		QSize viewport,
 		float factor,
-		const style::color &color) {
-	const auto &rgb = color->c.toRgb();
+		const QColor &color) {
+	const auto rgb = color.toRgb();
 	if (region.isEmpty()) {
 		return;
 	} else if (region.end() - region.begin() == 1
@@ -133,15 +156,18 @@ void BackgroundFiller::fill(
 	_bgTriangles.resize((region.end() - region.begin()) * 12);
 	auto coords = _bgTriangles.data();
 	for (const auto rect : region) {
-		FillRectVertices(coords, TransformRect(rect, viewport, factor));
+		FillRectTriangleVertices(
+			coords,
+			TransformRect(rect, viewport, factor));
 		coords += 12;
 	}
+	f.glUseProgram(_bgProgram->programId());
+	_bgProgram->setUniformValue("viewport", QSizeF(viewport * factor));
 	FillTriangles(
 		f,
 		_bgTriangles,
 		&*_bgBuffer,
 		&*_bgProgram,
-		viewport * factor,
 		rgb);
 }
 
diff --git a/ui/gl/gl_primitives.h b/ui/gl/gl_primitives.h
index 3ec0755..444b6ba 100644
--- a/ui/gl/gl_primitives.h
+++ b/ui/gl/gl_primitives.h
@@ -16,17 +16,22 @@ class QOpenGLFunctions;
 
 namespace Ui::GL {
 
-void FillRectVertices(float *coords, Rect rect);
-
+void FillRectTriangleVertices(float *coords, Rect rect);
 void FillTriangles(
 	QOpenGLFunctions &f,
 	gsl::span<const float> coords,
 	not_null<QOpenGLBuffer*> buffer,
 	not_null<QOpenGLShaderProgram*> program,
-	QSize viewportWithFactor,
 	const QColor &color,
 	Fn<void()> additional = nullptr);
 
+
+void FillRectangle(
+	QOpenGLFunctions &f,
+	not_null<QOpenGLShaderProgram*> program,
+	int skipVertices,
+	const QColor &color);
+
 void FillTexturedRectangle(
 	QOpenGLFunctions &f,
 	not_null<QOpenGLShaderProgram*> program,
@@ -42,7 +47,16 @@ public:
 		const QRegion &region,
 		QSize viewport,
 		float factor,
-		const style::color &color);
+		const QColor &color);
+
+	void fill(
+			QOpenGLFunctions &f,
+			const QRegion &region,
+			QSize viewport,
+			float factor,
+			const style::color &color) {
+		return fill(f, region, viewport, factor, color->c);
+	}
 
 private:
 	std::optional<QOpenGLBuffer> _bgBuffer;
diff --git a/ui/gl/gl_shader.cpp b/ui/gl/gl_shader.cpp
index 5e5d7f1..7a04d1e 100644
--- a/ui/gl/gl_shader.cpp
+++ b/ui/gl/gl_shader.cpp
@@ -88,6 +88,17 @@ uniform sampler2D v_texture;
 	};
 }
 
+ShaderPart FragmentGlobalOpacity() {
+	return {
+		.header = R"(
+uniform float g_opacity;
+)",
+		.body = R"(
+	result *= g_opacity;
+)",
+	};
+}
+
 ShaderPart VertexViewportTransform() {
 	return {
 		.header = R"(
diff --git a/ui/gl/gl_shader.h b/ui/gl/gl_shader.h
index 3ce7aa6..0a4e22e 100644
--- a/ui/gl/gl_shader.h
+++ b/ui/gl/gl_shader.h
@@ -24,6 +24,7 @@ struct ShaderPart {
 [[nodiscard]] ShaderPart VertexPassTextureCoord(char prefix = 'v');
 [[nodiscard]] ShaderPart FragmentSampleARGB32Texture();
 [[nodiscard]] ShaderPart FragmentSampleYUV420Texture();
+[[nodiscard]] ShaderPart FragmentGlobalOpacity();
 [[nodiscard]] ShaderPart VertexViewportTransform();
 [[nodiscard]] ShaderPart FragmentRoundCorners();
 [[nodiscard]] ShaderPart FragmentStaticColor();