Implement DrawTexture functionality (#2747)

* Implement DrawTexture functionality

* Non-NVIDIA support

* Disable some features that should not affect draw texture (slow path)

* Remove space from shader source

* Match 2D engine names

* Fix resolution scale and add missing XML docs

* Disable transform feedback for draw texture fallback

Ryujinx.Graphics.OpenGL/DrawTextureEmulation.cs

@@ -0,0 +1,138 @@
+using OpenTK.Graphics.OpenGL;
+using Ryujinx.Graphics.OpenGL.Image;
+using System;
+
+namespace Ryujinx.Graphics.OpenGL
+{
+    class DrawTextureEmulation
+    {
+        private const string VertexShader = @"#version 430 core
+
+uniform float srcX0;
+uniform float srcY0;
+uniform float srcX1;
+uniform float srcY1;
+
+layout (location = 0) out vec2 texcoord;
+
+void main()
+{
+    bool x1 = (gl_VertexID & 1) != 0;
+    bool y1 = (gl_VertexID & 2) != 0;
+    gl_Position = vec4(x1 ? 1 : -1, y1 ? -1 : 1, 0, 1);
+    texcoord = vec2(x1 ? srcX1 : srcX0, y1 ? srcY1 : srcY0);
+}";
+
+        private const string FragmentShader = @"#version 430 core
+
+layout (location = 0) uniform sampler2D tex;
+
+layout (location = 0) in vec2 texcoord;
+layout (location = 0) out vec4 colour;
+
+void main()
+{
+    colour = texture(tex, texcoord);
+}";
+
+        private int _vsHandle;
+        private int _fsHandle;
+        private int _programHandle;
+        private int _uniformSrcX0Location;
+        private int _uniformSrcY0Location;
+        private int _uniformSrcX1Location;
+        private int _uniformSrcY1Location;
+        private bool _initialized;
+
+        public void Draw(
+            TextureView texture,
+            Sampler sampler,
+            float x0,
+            float y0,
+            float x1,
+            float y1,
+            float s0,
+            float t0,
+            float s1,
+            float t1)
+        {
+            EnsureInitialized();
+
+            GL.UseProgram(_programHandle);
+
+            texture.Bind(0);
+            sampler.Bind(0);
+
+            if (x0 > x1)
+            {
+                float temp = s0;
+                s0 = s1;
+                s1 = temp;
+            }
+
+            if (y0 > y1)
+            {
+                float temp = t0;
+                t0 = t1;
+                t1 = temp;
+            }
+
+            GL.Uniform1(_uniformSrcX0Location, s0);
+            GL.Uniform1(_uniformSrcY0Location, t0);
+            GL.Uniform1(_uniformSrcX1Location, s1);
+            GL.Uniform1(_uniformSrcY1Location, t1);
+
+            GL.ViewportIndexed(0, MathF.Min(x0, x1), MathF.Min(y0, y1), MathF.Abs(x1 - x0), MathF.Abs(y1 - y0));
+
+            GL.DrawArrays(PrimitiveType.TriangleStrip, 0, 4);
+        }
+
+        private void EnsureInitialized()
+        {
+            if (_initialized)
+            {
+                return;
+            }
+
+            _initialized = true;
+
+            _vsHandle = GL.CreateShader(ShaderType.VertexShader);
+            _fsHandle = GL.CreateShader(ShaderType.FragmentShader);
+
+            GL.ShaderSource(_vsHandle, VertexShader);
+            GL.ShaderSource(_fsHandle, FragmentShader);
+
+            GL.CompileShader(_vsHandle);
+            GL.CompileShader(_fsHandle);
+
+            _programHandle = GL.CreateProgram();
+
+            GL.AttachShader(_programHandle, _vsHandle);
+            GL.AttachShader(_programHandle, _fsHandle);
+
+            GL.LinkProgram(_programHandle);
+
+            GL.DetachShader(_programHandle, _vsHandle);
+            GL.DetachShader(_programHandle, _fsHandle);
+
+            _uniformSrcX0Location = GL.GetUniformLocation(_programHandle, "srcX0");
+            _uniformSrcY0Location = GL.GetUniformLocation(_programHandle, "srcY0");
+            _uniformSrcX1Location = GL.GetUniformLocation(_programHandle, "srcX1");
+            _uniformSrcY1Location = GL.GetUniformLocation(_programHandle, "srcY1");
+        }
+
+        public void Dispose()
+        {
+            if (!_initialized)
+            {
+                return;
+            }
+
+            GL.DeleteShader(_vsHandle);
+            GL.DeleteShader(_fsHandle);
+            GL.DeleteProgram(_programHandle);
+
+            _initialized = false;
+        }
+    }
+}