X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Fgraphics%2Fshader.cpp;h=dbdeeb15552efa28699b4b7b50893e73ae9e10d3;hb=42db7d9d2286e50896ad172e2e4a8fbe65c8a4a9;hp=d771d9f943385f4709108b99c2f58540cd868db2;hpb=c5556cf5f6813887a3503433c021ccd2e7fae865;p=blobs.git

diff --git a/src/graphics/shader.cpp b/src/graphics/shader.cpp
index d771d9f..dbdeeb1 100644
--- a/src/graphics/shader.cpp
+++ b/src/graphics/shader.cpp
@@ -1,9 +1,13 @@
+#include "AlphaSprite.hpp"
+#include "Canvas.hpp"
+#include "CreatureSkin.hpp"
 #include "PlanetSurface.hpp"
 #include "Program.hpp"
 #include "Shader.hpp"
 #include "SunSurface.hpp"
 
 #include "ArrayTexture.hpp"
+#include "Texture.hpp"
 #include "../app/init.hpp"
 
 #include <algorithm>
@@ -13,6 +17,7 @@
 #include <stdexcept>
 #include <string>
 #include <glm/gtc/type_ptr.hpp>
+#include <glm/gtx/transform.hpp>
 
 
 namespace {
@@ -142,10 +147,18 @@ GLint Program::AttributeLocation(const GLchar *name) const noexcept {
 	return glGetAttribLocation(handle, name);
 }
 
+GLint Program::AttributeLocation(const std::string &name) const noexcept {
+	return AttributeLocation(name.c_str());
+}
+
 GLint Program::UniformLocation(const GLchar *name) const noexcept {
 	return glGetUniformLocation(handle, name);
 }
 
+GLint Program::UniformLocation(const std::string &name) const noexcept {
+	return UniformLocation(name.c_str());
+}
+
 
 void Program::Uniform(GLint loc, GLint val) noexcept {
 	glUniform1i(loc, val);
@@ -168,6 +181,8 @@ void Program::Uniform(GLint loc, const glm::mat4 &val) noexcept {
 }
 
 
+constexpr int PlanetSurface::MAX_LIGHTS;
+
 PlanetSurface::PlanetSurface()
 : prog() {
 	prog.LoadShader(
@@ -205,24 +220,28 @@ PlanetSurface::PlanetSurface()
 
 		"uniform sampler2DArray tex_sampler;\n"
 		"uniform vec3 normal;\n"
-		"uniform LightSource light;\n"
+		"uniform int num_lights;\n"
+		"uniform LightSource light[8];\n"
 
 		"out vec3 color;\n"
 
 		"void main() {\n"
 			"vec3 tex_color = texture(tex_sampler, frag_tex_uv).rgb;\n"
-			"vec3 to_light = light.position - vtx_viewspace;\n"
-			"float distance = length(to_light);\n"
-			"vec3 light_dir = normalize(to_light);\n"
-			"float attenuation = light.strength / (distance * distance);\n"
-			"vec3 ambient = tex_color * vec3(0.01, 0.01, 0.01);\n"
-			"vec3 diffuse = attenuation * max(0.0, dot(normal, light_dir)) * light.color * tex_color;\n"
-			"vec3 view_dir = vec3(0.0, 0.0, 1.0);\n"
-			"vec3 specular = vec3(0.0, 0.0, 0.0);\n"
-			"if (dot(normal, light_dir) >= 0.0) {\n"
-				"attenuation * light.color * pow(max(0.0, dot(reflect(-light_dir, normal), view_dir)), 25.0);\n"
+			"vec3 total_light = tex_color * vec3(0.1, 0.1, 0.1);\n"
+			"for (int i = 0; i < num_lights; ++i) {\n"
+				"vec3 to_light = light[i].position - vtx_viewspace;\n"
+				"float distance = length(to_light) + length(vtx_viewspace);\n"
+				"vec3 light_dir = normalize(to_light);\n"
+				"float attenuation = light[i].strength / (distance * distance);\n"
+				"vec3 diffuse = attenuation * max(0.0, dot(normal, light_dir)) * light[i].color * tex_color;\n"
+				"vec3 view_dir = vec3(0.0, 0.0, 1.0);\n"
+				"vec3 specular = vec3(0.0, 0.0, 0.0);\n"
+				"if (dot(normal, light_dir) >= 0.0) {\n"
+					"attenuation * light[i].color * pow(max(0.0, dot(reflect(-light_dir, normal), view_dir)), 25.0);\n"
+				"}\n"
+				"total_light = total_light + diffuse + specular;\n"
 			"}\n"
-			"color = ambient + diffuse + specular;\n"
+			"color = total_light;\n"
 		"}\n"
 	);
 	prog.Link();
@@ -235,9 +254,12 @@ PlanetSurface::PlanetSurface()
 	mvp_handle = prog.UniformLocation("MVP");
 	sampler_handle = prog.UniformLocation("tex_sampler");
 	normal_handle = prog.UniformLocation("normal");
-	light_position_handle = prog.UniformLocation("light.position");
-	light_color_handle = prog.UniformLocation("light.color");
-	light_strength_handle = prog.UniformLocation("light.strength");
+	num_lights_handle = prog.UniformLocation("num_lights");
+	for (int i = 0; i < MAX_LIGHTS; ++i) {
+		light_handle[3 * i + 0]  = prog.UniformLocation("light[" + std::to_string(i) + "].position");
+		light_handle[3 * i + 1]  = prog.UniformLocation("light[" + std::to_string(i) + "].color");
+		light_handle[3 * i + 2]  = prog.UniformLocation("light[" + std::to_string(i) + "].strength");
+	}
 }
 
 PlanetSurface::~PlanetSurface() {
@@ -251,6 +273,24 @@ void PlanetSurface::Activate() noexcept {
 	glDisable(GL_BLEND);
 }
 
+void PlanetSurface::SetM(const glm::mat4 &mm) noexcept {
+	m = mm;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void PlanetSurface::SetVP(const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
 void PlanetSurface::SetMVP(const glm::mat4 &mm, const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
 	m = mm;
 	v = vv;
@@ -272,10 +312,14 @@ void PlanetSurface::SetTexture(ArrayTexture &tex) noexcept {
 	prog.Uniform(sampler_handle, GLint(0));
 }
 
-void PlanetSurface::SetLight(const glm::vec3 &pos, const glm::vec3 &color, float strength) noexcept {
-	prog.Uniform(light_position_handle, pos);
-	prog.Uniform(light_color_handle, color);
-	prog.Uniform(light_strength_handle, strength);
+void PlanetSurface::SetLight(int n, const glm::vec3 &pos, const glm::vec3 &color, float strength) noexcept {
+	prog.Uniform(light_handle[3 * n + 0], pos);
+	prog.Uniform(light_handle[3 * n + 1], color);
+	prog.Uniform(light_handle[3 * n + 2], strength);
+}
+
+void PlanetSurface::SetNumLights(int n) noexcept {
+	prog.Uniform(num_lights_handle, std::min(MAX_LIGHTS, n));
 }
 
 
@@ -405,6 +449,24 @@ void SunSurface::Activate() noexcept {
 	glDisable(GL_BLEND);
 }
 
+void SunSurface::SetM(const glm::mat4 &mm) noexcept {
+	m = mm;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void SunSurface::SetVP(const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
 void SunSurface::SetMVP(const glm::mat4 &mm, const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
 	m = mm;
 	v = vv;
@@ -426,5 +488,448 @@ void SunSurface::Draw() const noexcept {
 	vao.DrawTriangles(36);
 }
 
+
+constexpr int CreatureSkin::MAX_LIGHTS;
+
+CreatureSkin::CreatureSkin()
+: prog() {
+	prog.LoadShader(
+		GL_VERTEX_SHADER,
+		"#version 330 core\n"
+
+		"layout(location = 0) in vec3 vtx_position;\n"
+		"layout(location = 1) in vec3 vtx_normal;\n"
+		"layout(location = 2) in vec3 vtx_tex_uv;\n"
+
+		"uniform mat4 M;\n"
+		"uniform mat4 MV;\n"
+		"uniform mat4 MVP;\n"
+
+		"out vec3 vtx_viewspace;\n"
+		"out vec3 frag_tex_uv;\n"
+		"out vec3 normal;\n"
+
+		"void main() {\n"
+			"gl_Position = MVP * vec4(vtx_position, 1);\n"
+			"vtx_viewspace = (MV * vec4(vtx_position, 1)).xyz;\n"
+			"normal = normalize((MV * vec4(vtx_normal, 0)).xyz);\n"
+			"frag_tex_uv = vtx_tex_uv;\n"
+		"}\n"
+	);
+	prog.LoadShader(
+		GL_FRAGMENT_SHADER,
+		"#version 330 core\n"
+
+		"struct LightSource {\n"
+			"vec3 position;\n"
+			"vec3 color;\n"
+			"float strength;\n"
+		"};\n"
+
+		"in vec3 vtx_viewspace;\n"
+		"in vec3 frag_tex_uv;\n"
+		"in vec3 normal;\n"
+
+		"uniform sampler2DArray tex_sampler;\n"
+		"uniform int num_lights;\n"
+		"uniform LightSource light[8];\n"
+
+		"out vec3 color;\n"
+
+		"void main() {\n"
+			"vec3 tex_color = texture(tex_sampler, frag_tex_uv).rgb;\n"
+			"vec3 total_light = tex_color * vec3(0.1, 0.1, 0.1);\n"
+			"for (int i = 0; i < num_lights; ++i) {\n"
+				"vec3 to_light = light[i].position - vtx_viewspace;\n"
+				"float distance = length(to_light) + length(vtx_viewspace);\n"
+				"vec3 light_dir = normalize(to_light);\n"
+				"float attenuation = light[i].strength / (distance * distance);\n"
+				"vec3 diffuse = attenuation * max(0.0, dot(normal, light_dir)) * light[i].color * tex_color;\n"
+				"vec3 view_dir = vec3(0.0, 0.0, 1.0);\n"
+				"vec3 specular = vec3(0.0, 0.0, 0.0);\n"
+				"if (dot(normal, light_dir) >= 0.0) {\n"
+					"attenuation * light[i].color * pow(max(0.0, dot(reflect(-light_dir, normal), view_dir)), 25.0);\n"
+				"}\n"
+				"total_light = total_light + diffuse + specular;\n"
+			"}\n"
+			"color = total_light;\n"
+		"}\n"
+	);
+	prog.Link();
+	if (!prog.Linked()) {
+		prog.Log(std::cerr);
+		throw std::runtime_error("link program");
+	}
+	m_handle = prog.UniformLocation("M");
+	mv_handle = prog.UniformLocation("MV");
+	mvp_handle = prog.UniformLocation("MVP");
+	sampler_handle = prog.UniformLocation("tex_sampler");
+	num_lights_handle = prog.UniformLocation("num_lights");
+	for (int i = 0; i < MAX_LIGHTS; ++i) {
+		light_handle[3 * i + 0]  = prog.UniformLocation("light[" + std::to_string(i) + "].position");
+		light_handle[3 * i + 1]  = prog.UniformLocation("light[" + std::to_string(i) + "].color");
+		light_handle[3 * i + 2]  = prog.UniformLocation("light[" + std::to_string(i) + "].strength");
+	}
+}
+
+CreatureSkin::~CreatureSkin() {
+}
+
+void CreatureSkin::Activate() noexcept {
+	prog.Use();
+	glEnable(GL_DEPTH_TEST);
+	glDepthFunc(GL_LESS);
+	glEnable(GL_CULL_FACE);
+	glDisable(GL_BLEND);
+}
+
+void CreatureSkin::SetM(const glm::mat4 &mm) noexcept {
+	m = mm;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void CreatureSkin::SetVP(const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void CreatureSkin::SetMVP(const glm::mat4 &mm, const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	m = mm;
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void CreatureSkin::SetTexture(ArrayTexture &tex) noexcept {
+	glActiveTexture(GL_TEXTURE0);
+	tex.Bind();
+	prog.Uniform(sampler_handle, GLint(0));
+}
+
+void CreatureSkin::SetLight(int n, const glm::vec3 &pos, const glm::vec3 &color, float strength) noexcept {
+	prog.Uniform(light_handle[3 * n + 0], pos);
+	prog.Uniform(light_handle[3 * n + 1], color);
+	prog.Uniform(light_handle[3 * n + 2], strength);
+}
+
+void CreatureSkin::SetNumLights(int n) noexcept {
+	prog.Uniform(num_lights_handle, std::min(MAX_LIGHTS, n));
+}
+
+
+AlphaSprite::AlphaSprite()
+: prog() {
+	prog.LoadShader(
+		GL_VERTEX_SHADER,
+		"#version 330 core\n"
+
+		"layout(location = 0) in vec3 vtx_position;\n"
+		"layout(location = 1) in vec2 vtx_texture;\n"
+
+		"uniform mat4 M;\n"
+		"uniform mat4 MV;\n"
+		"uniform mat4 MVP;\n"
+
+		"out vec2 frag_tex_uv;\n"
+
+		"void main() {\n"
+			"gl_Position = MVP * vec4(vtx_position, 1);\n"
+			"frag_tex_uv = vtx_texture;\n"
+		"}\n"
+	);
+	prog.LoadShader(
+		GL_FRAGMENT_SHADER,
+		"#version 330 core\n"
+
+		"in vec2 frag_tex_uv;\n"
+
+		"uniform sampler2D tex_sampler;\n"
+		"uniform vec4 fg_color;\n"
+		"uniform vec4 bg_color;\n"
+
+		"out vec4 color;\n"
+
+		"void main() {\n"
+			"vec4 tex_color = texture(tex_sampler, frag_tex_uv);\n"
+			"vec4 factor = mix(bg_color, fg_color, tex_color.a);\n"
+			"color = vec4((tex_color * factor).rgb, factor.a);\n"
+		"}\n"
+	);
+	prog.Link();
+	if (!prog.Linked()) {
+		prog.Log(std::cerr);
+		throw std::runtime_error("link program");
+	}
+	m_handle = prog.UniformLocation("M");
+	mv_handle = prog.UniformLocation("MV");
+	mvp_handle = prog.UniformLocation("MVP");
+	sampler_handle = prog.UniformLocation("tex_sampler");
+	fg_color_handle = prog.UniformLocation("fg_color");
+	bg_color_handle = prog.UniformLocation("bg_color");
+
+	vao.Bind();
+	vao.BindAttributes();
+	vao.EnableAttribute(0);
+	vao.EnableAttribute(1);
+	vao.AttributePointer<glm::vec3>(0, false, offsetof(Attributes, position));
+	vao.AttributePointer<glm::vec2>(1, false, offsetof(Attributes, texture));
+	vao.ReserveAttributes(4, GL_STATIC_DRAW);
+	{
+		auto attrib = vao.MapAttributes(GL_WRITE_ONLY);
+		attrib[0].position = glm::vec3(-0.5f, -0.5f, 0.0f);
+		attrib[0].texture = glm::vec2(0.0f, 0.0f);
+		attrib[1].position = glm::vec3(-0.5f,  0.5f, 0.0f);
+		attrib[1].texture = glm::vec2(0.0f, 1.0f);
+		attrib[2].position = glm::vec3( 0.5f, -0.5f, 0.0f);
+		attrib[2].texture = glm::vec2(1.0f, 0.0f);
+		attrib[3].position = glm::vec3( 0.5f,  0.5f, 0.0f);
+		attrib[3].texture = glm::vec2(1.0f, 1.0f);
+	}
+	vao.BindElements();
+	vao.ReserveElements(7, GL_STATIC_DRAW);
+	{
+		auto element = vao.MapElements(GL_WRITE_ONLY);
+		element[ 0] = 0;
+		element[ 1] = 1;
+		element[ 2] = 2;
+		element[ 3] = 3;
+	}
+	vao.Unbind();
+}
+
+AlphaSprite::~AlphaSprite() {
+}
+
+void AlphaSprite::Activate() noexcept {
+	prog.Use();
+	glEnable(GL_DEPTH_TEST);
+	glDepthFunc(GL_LESS);
+	glEnable(GL_CULL_FACE);
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+}
+
+void AlphaSprite::SetM(const glm::mat4 &mm) noexcept {
+	m = mm;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void AlphaSprite::SetVP(const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void AlphaSprite::SetMVP(const glm::mat4 &mm, const glm::mat4 &vv, const glm::mat4 &pp) noexcept {
+	m = mm;
+	v = vv;
+	p = pp;
+	mv = v * m;
+	mvp = p * mv;
+	prog.Uniform(m_handle, m);
+	prog.Uniform(mv_handle, mv);
+	prog.Uniform(mvp_handle, mvp);
+}
+
+void AlphaSprite::SetTexture(Texture &tex) noexcept {
+	glActiveTexture(GL_TEXTURE0);
+	tex.Bind();
+	prog.Uniform(sampler_handle, GLint(0));
+}
+
+void AlphaSprite::SetFgColor(const glm::vec4 &color) noexcept {
+	prog.Uniform(fg_color_handle, color);
+}
+
+void AlphaSprite::SetBgColor(const glm::vec4 &color) noexcept {
+	prog.Uniform(bg_color_handle, color);
+}
+
+void AlphaSprite::DrawRect() const noexcept {
+	vao.Bind();
+	vao.DrawTriangleStrip(4);
+}
+
+
+Canvas::Canvas()
+: prog()
+, vao() {
+	prog.LoadShader(
+		GL_VERTEX_SHADER,
+		"#version 330 core\n"
+
+		"layout(location = 0) in vec2 vtx_position;\n"
+
+		"uniform mat4 P;\n"
+		"uniform float z;\n"
+
+		"void main() {\n"
+			// disamond rule adjust
+			//"vec3 position = vtx_position + vec3(0.5, 0.5, 0.0);\n"
+			"gl_Position = P * vec4(vtx_position, z, 1);\n"
+		"}\n"
+	);
+	prog.LoadShader(
+		GL_FRAGMENT_SHADER,
+		"#version 330 core\n"
+
+		"uniform vec4 c;\n"
+
+		"out vec4 color;\n"
+
+		"void main() {\n"
+			"color = c;\n"
+		"}\n"
+	);
+	prog.Link();
+	if (!prog.Linked()) {
+		prog.Log(std::cerr);
+		throw std::runtime_error("link program");
+	}
+	p_handle = prog.UniformLocation("P");
+	z_handle = prog.UniformLocation("z");
+	c_handle = prog.UniformLocation("c");
+
+	vao.Bind();
+	vao.BindAttributes();
+	vao.EnableAttribute(0);
+	vao.AttributePointer<glm::vec2>(0, false, offsetof(Attributes, position));
+	vao.ReserveAttributes(255, GL_DYNAMIC_DRAW);
+	vao.BindElements();
+	vao.ReserveElements(255, GL_DYNAMIC_DRAW);
+	vao.Unbind();
+}
+
+Canvas::~Canvas() {
+}
+
+void Canvas::Resize(float w, float h) noexcept {
+	prog.Uniform(p_handle, glm::ortho(0.0f, w, h, 0.0f, 1.0e4f, -1.0e4f));
+}
+
+void Canvas::ZIndex(float z) noexcept {
+	prog.Uniform(z_handle, -z);
+}
+
+void Canvas::SetColor(const glm::vec4 &color) noexcept {
+	prog.Uniform(c_handle, color);
+}
+
+void Canvas::Activate() noexcept {
+	prog.Use();
+	glEnable(GL_DEPTH_TEST);
+	glDepthFunc(GL_LESS);
+	glEnable(GL_CULL_FACE);
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+}
+
+void Canvas::DrawLine(const glm::vec2 &p1, const glm::vec2 &p2, float width) {
+	glm::vec2 d = glm::normalize(p2 - p1) * (width * 0.5f);
+	glm::vec2 n = glm::vec2(d.y, -d.x);
+	vao.Bind();
+	vao.BindAttributes();
+	{
+		auto attr = vao.MapAttributes(GL_WRITE_ONLY);
+		attr[0].position = p1 - d + n;
+		attr[1].position = p1 - d - n;
+		attr[2].position = p2 + d + n;
+		attr[3].position = p2 + d - n;
+	}
+	vao.BindElements();
+	{
+		auto elem = vao.MapElements(GL_WRITE_ONLY);
+		elem[0] = 0;
+		elem[1] = 1;
+		elem[2] = 2;
+		elem[3] = 3;
+	}
+	vao.DrawTriangleStrip(4);
+	vao.Unbind();
+}
+
+void Canvas::DrawRect(const glm::vec2 &p1, const glm::vec2 &p2, float width) {
+	glm::vec2 min(std::min(p1.x, p2.x), std::min(p1.y, p2.y));
+	glm::vec2 max(std::max(p1.x, p2.x), std::max(p1.y, p2.y));
+	glm::vec2 dg1(min.x, max.y);
+	glm::vec2 dg2(max.x, min.y);
+	glm::vec2 d(width * 0.5f, width * 0.5f);
+	glm::vec2 n(d.y, -d.x);
+	vao.Bind();
+	vao.BindAttributes();
+	{
+		auto attr = vao.MapAttributes(GL_WRITE_ONLY);
+		attr[0].position = min + d;
+		attr[1].position = min - d;
+		attr[2].position = dg1 + n;
+		attr[3].position = dg1 - n;
+		attr[4].position = max - d;
+		attr[5].position = max + d;
+		attr[6].position = dg2 - n;
+		attr[7].position = dg2 + n;
+	}
+	vao.BindElements();
+	{
+		auto elem = vao.MapElements(GL_WRITE_ONLY);
+		elem[0] = 0;
+		elem[1] = 1;
+		elem[2] = 2;
+		elem[3] = 3;
+		elem[4] = 4;
+		elem[5] = 5;
+		elem[6] = 6;
+		elem[7] = 7;
+		elem[8] = 0;
+		elem[9] = 1;
+	}
+	vao.DrawTriangleStrip(10);
+	vao.Unbind();
+}
+
+void Canvas::FillRect(const glm::vec2 &p1, const glm::vec2 &p2) {
+	glm::vec2 min(std::min(p1.x, p2.x), std::min(p1.y, p2.y));
+	glm::vec2 max(std::max(p1.x, p2.x), std::max(p1.y, p2.y));
+	glm::vec2 dg1(min.x, max.y);
+	glm::vec2 dg2(max.x, min.y);
+	vao.Bind();
+	vao.BindAttributes();
+	{
+		auto attr = vao.MapAttributes(GL_WRITE_ONLY);
+		attr[0].position = min;
+		attr[1].position = dg1;
+		attr[2].position = dg2;
+		attr[3].position = max;
+	}
+	vao.BindElements();
+	{
+		auto elem = vao.MapElements(GL_WRITE_ONLY);
+		elem[0] = 0;
+		elem[1] = 1;
+		elem[2] = 2;
+		elem[3] = 3;
+	}
+	vao.DrawTriangleStrip(4);
+	vao.Unbind();
+}
+
 }
 }