From 77125540e699ecc0936c2c90806f45c1b41804a2 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 16 Oct 2020 07:44:13 +0300
Subject: [PATCH] Implement texture rendering in gfx::painter

---
 libs/gfx/include/psemek/gfx/painter.hpp |  3 +
 libs/gfx/source/painter.cpp             | 85 ++++++++++++++++++++++++-
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/libs/gfx/include/psemek/gfx/painter.hpp b/libs/gfx/include/psemek/gfx/painter.hpp
index 52f1ce4b..63aac7db 100644
--- a/libs/gfx/include/psemek/gfx/painter.hpp
+++ b/libs/gfx/include/psemek/gfx/painter.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <psemek/gfx/color.hpp>
+#include <psemek/gfx/texture.hpp>
 #include <psemek/geom/vector.hpp>
 #include <psemek/geom/point.hpp>
 #include <psemek/geom/matrix.hpp>
@@ -57,6 +58,8 @@ 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);
+
 		// 3D
 		void axes(geom::point<float, 3> const & p, float length, float width);
 		void sphere(geom::point<float, 3> const & p, float radius, color const & c, int quality = 6);
diff --git a/libs/gfx/source/painter.cpp b/libs/gfx/source/painter.cpp
index 00fa6f9a..85e87f61 100644
--- a/libs/gfx/source/painter.cpp
+++ b/libs/gfx/source/painter.cpp
@@ -74,6 +74,38 @@ void main()
 }
 )";
 
+static const char texture_vertex_source[] =
+R"(#version 330
+
+uniform mat4 u_transform;
+
+layout (location = 0) in vec4 in_position;
+layout (location = 1) in vec2 in_texcoord;
+
+out vec2 texcoord;
+
+void main()
+{
+	gl_Position = u_transform * in_position;
+	texcoord = in_texcoord;
+}
+)";
+
+static const char texture_fragment_source[] =
+R"(#version 330
+
+uniform sampler2D u_texture;
+
+in vec2 texcoord;
+
+out vec4 out_color;
+
+void main()
+{
+	out_color = texture(u_texture, texcoord);
+}
+)";
+
 namespace psemek::gfx
 {
 
@@ -92,10 +124,18 @@ namespace psemek::gfx
 			geom::point<std::uint16_t, 2> texcoord;
 		};
 
+		struct texture_vertex
+		{
+			geom::point<float, 3> position;
+			geom::point<std::uint16_t, 2> texcoord;
+		};
+
 		gfx::program program{vertex_source, fragment_source};
 		gfx::program text_program{text_vertex_source, text_fragment_source};
+		gfx::program texture_program{texture_vertex_source, texture_fragment_source};
 		gfx::mesh mesh;
 		gfx::mesh text_mesh;
+		gfx::mesh texture_mesh;
 
 		std::vector<vertex> vertices;
 		std::vector<std::uint32_t> indices;
@@ -103,12 +143,22 @@ namespace psemek::gfx
 		std::vector<text_vertex> text_vertices;
 		std::vector<std::uint32_t> text_indices;
 
-		gfx::texture_2d font_texture;
+		struct texture_render_data
+		{
+			std::vector<texture_vertex> vertices;
+			std::vector<std::uint32_t> indices;
+			texture_2d const * texture;
+		};
+
+		std::vector<texture_render_data> textures;
+
+		texture_2d font_texture;
 
 		impl()
 		{
 			mesh.setup<geom::vector<float, 3>, gfx::normalized<color_rgba>>();
 			text_mesh.setup<geom::point<float, 3>, gfx::normalized<color_rgba>, geom::point<std::uint16_t, 2>>();
+			texture_mesh.setup<geom::point<float, 3>, gfx::normalized<geom::point<std::uint16_t, 2>>>();
 
 			util::memory_istream font_data(resource::font_9x12);
 			font_texture.load(gfx::read_pbm(font_data));
@@ -231,6 +281,24 @@ 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)
+	{
+		impl::texture_render_data data;
+		data.texture = &texture;
+
+		data.indices = {0, 1, 2, 2, 1, 3};
+
+		std::uint16_t lo = 0;
+		std::uint16_t hi = 65535;
+
+		data.vertices.push_back({{box[0].min, box[1].min, 0.f}, {lo, lo}});
+		data.vertices.push_back({{box[0].max, box[1].min, 0.f}, {hi, lo}});
+		data.vertices.push_back({{box[0].min, box[1].max, 0.f}, {lo, hi}});
+		data.vertices.push_back({{box[0].max, box[1].max, 0.f}, {hi, hi}});
+
+		impl().textures.push_back(data);
+	}
+
 	void painter::axes(geom::point<float, 3> const & p, float length, float width)
 	{
 		geom::vector<float, 3> const d[3]
@@ -450,6 +518,10 @@ namespace psemek::gfx
 
 	void painter::render(geom::matrix<float, 4, 4> const & transform)
 	{
+		gl::ActiveTexture(gl::TEXTURE0);
+
+		gl::Disable(gl::CULL_FACE);
+
 		impl().mesh.load(impl().vertices, impl().indices, gl::TRIANGLES, gl::STREAM_DRAW);
 		impl().vertices.clear();
 		impl().indices.clear();
@@ -468,6 +540,17 @@ namespace psemek::gfx
 		impl().text_program["u_texture_size"] = impl().font_texture.size();
 		impl().font_texture.bind();
 		impl().text_mesh.draw();
+
+		impl().texture_program.bind();
+		impl().texture_program["u_transform"] = transform;
+		impl().texture_program["u_texture"] = 0;
+		for (auto const & data : impl().textures)
+		{
+			impl().texture_mesh.load(data.vertices, data.indices, gl::TRIANGLES, gl::STREAM_DRAW);
+			data.texture->bind();
+			impl().texture_mesh.draw();
+		}
+		impl().textures.clear();
 	}
 
 }