From f8d127d700aac533ddf508739cdbad1dba8a196a Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 17 Feb 2021 14:55:17 +0300
Subject: [PATCH] Support blending textures with a color in painter

---
 libs/gfx/include/psemek/gfx/painter.hpp |  2 +-
 libs/gfx/source/painter.cpp             | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/libs/gfx/include/psemek/gfx/painter.hpp b/libs/gfx/include/psemek/gfx/painter.hpp
index d143e4a0..de697234 100644
--- a/libs/gfx/include/psemek/gfx/painter.hpp
+++ b/libs/gfx/include/psemek/gfx/painter.hpp
@@ -61,7 +61,7 @@ namespace psemek::gfx
 		geom::vector<float, 2> text_size(std::string_view str, font f = font::font_9x12, float scale = 1.f);
 		void text(geom::point<float, 2> const & p, std::string_view str, text_options const & opts);
 
-		void texture(texture_2d const & texture, geom::box<float, 2> const & box);
+		void texture(texture_2d const & texture, geom::box<float, 2> const & box, color const & c = {0, 0, 0, 0});
 
 		// 3D
 		void axes(geom::point<float, 3> const & p, float length, float width);
diff --git a/libs/gfx/source/painter.cpp b/libs/gfx/source/painter.cpp
index 16b9b819..43973172 100644
--- a/libs/gfx/source/painter.cpp
+++ b/libs/gfx/source/painter.cpp
@@ -95,6 +95,7 @@ static const char texture_fragment_source[] =
 R"(#version 330
 
 uniform sampler2D u_texture;
+uniform vec4 u_color;
 
 in vec2 texcoord;
 
@@ -102,7 +103,9 @@ out vec4 out_color;
 
 void main()
 {
-	out_color = texture(u_texture, texcoord);
+	vec4 color = texture(u_texture, texcoord);
+	color.rgb = mix(color.rgb, u_color.rgb, u_color.a);
+	out_color = color;
 }
 )";
 
@@ -148,6 +151,7 @@ namespace psemek::gfx
 			std::vector<texture_vertex> vertices;
 			std::vector<std::uint32_t> indices;
 			texture_2d const * texture;
+			color_rgba c;
 		};
 
 		std::vector<texture_render_data> textures;
@@ -281,10 +285,11 @@ namespace psemek::gfx
 		text3d(geom::point{p[0], p[1], 0.f}, str, opts, geom::matrix<float, 3, 3>::identity());
 	}
 
-	void painter::texture(gfx::texture_2d const & texture, geom::box<float, 2> const & box)
+	void painter::texture(gfx::texture_2d const & texture, geom::box<float, 2> const & box, color const & c)
 	{
 		impl::texture_render_data data;
 		data.texture = &texture;
+		data.c = c;
 
 		data.indices = {0, 1, 2, 2, 1, 3};
 
@@ -563,6 +568,7 @@ namespace psemek::gfx
 		impl().texture_program["u_texture"] = 0;
 		for (auto const & data : impl().textures)
 		{
+			impl().texture_program["u_color"] = to_colorf(data.c);
 			impl().texture_mesh.load(data.vertices, data.indices, gl::TRIANGLES, gl::STREAM_DRAW);
 			data.texture->bind();
 			impl().texture_mesh.draw();