3: Add texture support

examples/Playground/Program.fs

@@ -26,13 +26,19 @@ type GameState =
       Triangles = Primitives.ShadedObject.Default }
 
 let private initHandler (config:Config<GameState>) =
-  let fragmentPaths = ["Resources/Shaders/fragment.glsl"]
-  let vertexPaths = ["Resources/Shaders/vertex.glsl"]
+  let fragmentPaths = ["Resources/Shaders/Texture/fragment.glsl"]
+  let vertexPaths = ["Resources/Shaders/Texture/vertex.glsl"]
   let transform =
     { Transform.Default() with
         Scale = (1.0f, 1.0f, 1.0f)
         Rotation = (0.0f, 0.0f, 0.0f) }
-  match Primitives.ShadedObject.CreateQuad vertexPaths fragmentPaths transform 1.8f 1.0f with
+  match Primitives.ShadedObject.CreateQuad
+    vertexPaths
+    fragmentPaths
+    transform
+    1.8f
+    1.0f
+    (Types.Texture2D.FromPath "Resources/Textures/smiley.png" |> Some) with
   | Some primitive ->
     { config with
         State.Triangles = primitive }

examples/Playground/Resources/Shaders/vertex.glsl → examples/Playground/Resources/Shaders/Scanlines/vertex.glsl

@@ -1,6 +1,6 @@
 #version 330 core
 
-layout (location = 0) in vec3 in_position;   // the in_position variable has attribute position 0
+layout (location = 0) in vec3 in_position;   // the in_position variable has attribute position 0\
 
 void main()
 {

examples/Playground/Resources/Shaders/Texture/fragment.glsl

@@ -0,0 +1,19 @@
+#version 330 core
+
+in vec2 out_texture_coordinate;
+
+out vec4 out_frag_color;
+
+uniform vec2 in_viewport;
+uniform sampler2D in_texture;
+
+void main()
+{
+  // out_frag_color = texture(in_texture, TexCoord)
+  out_frag_color = vec4(
+    1.0f - out_texture_coordinate.x,
+    1.0f - out_texture_coordinate.y,
+    0.0f,
+    1.0f
+  );
+} 

examples/Playground/Resources/Shaders/Texture/vertex.glsl

@@ -0,0 +1,12 @@
+#version 330 core
+
+layout (location = 0) in vec3 in_position;   // the in_position variable has attribute position 0
+layout (location = 1) in vec2 in_tex_coordinate;   // the in_tex_coordinate variable has attribute position 1
+
+out vec2 out_texture_coordinate;
+
+void main()
+{
+    gl_Position = vec4(in_position.x, in_position.y, in_position.z, 1.0);
+    out_texture_coordinate = in_tex_coordinate;
+}

issues/in-progress.md

@@ -6,7 +6,7 @@ Once completed, move the issue into [closed](./closed.md), and also close it wit
 
 ### [Issue Link](https://github.com/ExoKomodo/openwomb/issues/3)
 
-### Branch - [3_sprites](https://github.com/exokomodo/openwomb/tree/3_sprites)
+### [Branch](https://github.com/exokomodo/openwomb/tree/3_textures)
 
 ### Overview
 
@@ -20,10 +20,11 @@ This issue is to only implement the OpenGL way, as it provides a general-purpose
 ### Instructions
 
 1. Read the [OpenGL tutorial for rendering textures to a quad](https://learnopengl.com/Getting-started/Textures). Now prepare for implementation.
-1. Will require some changes to the [Primitives.ShadedObject.From function](./src/Womb/Graphics/Primitives.fs)
-1. Will require some changes to the [Primitives.ShadedObject.UseMvpShader function](./src/Womb/Graphics/Primitives.fs)
-1. Will require some changes to the [example shaders in the Playground example](./examples/Playground/Resources/Shaders/)
+1. Will require implementation of [glGenTextures in OpenGL1.1 API](../src/Womb/Backends/OpenGL/Api/OpenGL1_1.fs). Copy the pattern used with [glGenBuffers in OpenGL1.5 API](../src/Womb/Backends/OpenGL/Api/OpenGL1_5.fs), providing a helper for condition that `n=1`.
+1. Will require some changes to the [Primitives.ShadedObject.From function](../src/Womb/Graphics/Primitives.fs)
+1. Will require some changes to the [Primitives.ShadedObject.UseMvpShader function](../src/Womb/Graphics/Primitives.fs)
+1. Will require some changes to the [example shaders in the Playground example](../examples/Playground/Resources/Shaders/)
 
 ### Acceptance Criteria
 
-Be able to render an image to a shaded quad. To demonstrate this, modify the [Playground example](./examples/Playground) to render the [hello_world.bmp](./examples/Playground/Resources/Textures/hello_world.bmp). For proper completeness, demonstrate how we can color the texture in the shader as well.
+Be able to render an image to a shaded quad. To demonstrate this, modify the [Playground example](../examples/Playground) to render the [hello_world.bmp](../examples/Playground/Resources/Textures/hello_world.bmp). For proper completeness, demonstrate how we can color the texture in the shader as well.

src/ThirdParty/SDL2/Image.cs

@@ -89,13 +89,13 @@ public static SDL.SDL_version IMG_Linked_Version()
 
         /* IntPtr refers to an SDL_Surface* */
         [DllImport(nativeLibName, EntryPoint = "IMG_Load", CallingConvention = CallingConvention.Cdecl)]
-        private static extern unsafe IntPtr INTERNAL_IMG_Load(
+        private static extern unsafe SDL.SDL_Surface* INTERNAL_IMG_Load(
             byte* file
         );
-        public static unsafe IntPtr IMG_Load(string file)
+        public static unsafe SDL.SDL_Surface* IMG_Load(string file)
         {
             byte* utf8File = SDL.Utf8EncodeHeap(file);
-            IntPtr handle = INTERNAL_IMG_Load(
+            SDL.SDL_Surface* handle = INTERNAL_IMG_Load(
                 utf8File
             );
             Marshal.FreeHGlobal((IntPtr)utf8File);

src/ThirdParty/SDL2/SDL2Bindings.cs

@@ -4319,7 +4319,7 @@ uint color
 
         /* surface refers to an SDL_Surface* */
         [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
-        public static extern void SDL_FreeSurface(IntPtr surface);
+        public static extern unsafe void SDL_FreeSurface(SDL_Surface* surface);
 
         /* surface refers to an SDL_Surface* */
         [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]

src/Womb/Backends/OpenGL/Api/Constants/OpenGL1_0.fs

@@ -348,4 +348,4 @@ let GL_TEXTURE_WRAP_S = 0x2802u
 [<Literal>]
 let GL_TEXTURE_WRAP_T = 0x2803u
 [<Literal>]
-let GL_REPEAT = 0x2901u
+let GL_REPEAT = 0x2901u

src/Womb/Backends/OpenGL/Api/OpenGL1_1.fs

@@ -1,8 +1,11 @@
 [<AutoOpen>]
 module Womb.Backends.OpenGL.Api.OpenGL1_1
 
+#nowarn "9" // Unverifiable IL due to fixed expression and NativePtr library usage
+
 open Womb.Backends.OpenGL.Api.Common
 open Womb.Logging
+open Microsoft.FSharp.NativeInterop
 
 type private DrawArrays = delegate of uint * int * int -> unit
 let mutable private _glDrawArrays =
@@ -70,10 +73,18 @@ let mutable private _glDeleteTextures =
   DeleteTextures(fun _ _ -> warn (notLinked<DeleteTextures>()))
 let glDeleteTextures n textures = _glDeleteTextures.Invoke(n, textures)
 
-type private GenTextures = delegate of int * unativeint -> unit
+type private GenTextures = delegate of int * nativeptr<uint> -> unit
 let mutable private _glGenTextures =
   GenTextures(fun _ _ -> warn (notLinked<GenTextures>()))
-let glGenTextures n textures = _glGenTextures.Invoke(n, textures)
+let glGenTextures n =
+  let textures = Array.zeroCreate n
+  use ptr = fixed (&(textures.[0])) in
+    _glGenTextures.Invoke(n, ptr)
+  textures
+let glGenTexture() =
+  let ptr = NativePtr.stackalloc<uint> 1
+  _glGenTextures.Invoke(1, ptr)
+  NativePtr.get ptr 0
 
 type private IsTexture = delegate of uint -> unit
 let mutable private _glIsTexture =

src/Womb/Graphics/Primitives.fs

@@ -14,19 +14,50 @@ type ShadedObjectContext =
     VBO: uint;
     EBO: uint;
     Vertices: array<single>;
-    Indices: array<uint>; }
+    Indices: array<uint>;
+    Texture: uint; }
 
     static member Default () =
       { VAO = 0u
         VBO = 0u
         EBO = 0u
         Vertices = Array.empty
-        Indices = Array.empty }
+        Indices = Array.empty
+        Texture = 0u }
 
-    static member From (vertices) (indices) : ShadedObjectContext =
+    static member From (vertices) (indices) (textureOpt: option<Texture2D>) : ShadedObjectContext =
       let vao = glGenVertexArray()
       let vbo = glGenBuffer()
       let ebo = glGenBuffer()
+      let textureId =
+        match textureOpt with
+        | Some texture ->
+          let id = glGenTexture()
+          glBindTexture GL_TEXTURE_2D id
+
+          // NOTE: Eventually we will add texturing options for the individual texture, but for now let's set some defaults
+          glTexParameteri GL_TEXTURE_2D GL_TEXTURE_WRAP_S (int GL_REPEAT)
+          glTexParameteri GL_TEXTURE_2D GL_TEXTURE_WRAP_T (int GL_REPEAT)
+          glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER (int GL_LINEAR_MIPMAP_LINEAR)
+          glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER (int GL_LINEAR)
+
+          glTexImage2D
+            GL_TEXTURE_2D    // specifies the dimensional behavior of a texture: 1D is a line, 2D is a normal flat texture, 3D is a volumetric texture, like when a model is cut open and you want to show the interior of the object: https://stackoverflow.com/a/7329678
+            0                // mipmap level to use (clamped to 0 for now)
+            (int GL_RGB)     // format of output texture
+            texture.Width    // width of resulting texture
+            texture.Height   // height of resulting texture
+            0                // always 0, for legacy reasons
+            GL_RGB           // format of source image
+            GL_UNSIGNED_BYTE // datatype of source image
+            texture.Data     // image data
+          glGenerateMipmap GL_TEXTURE_2D
+
+          match texture.Surface with
+          | Some surface -> SDL2Bindings.SDL.SDL_FreeSurface(surface)
+          | None -> ()
+          id
+        | None -> 0u
 
       glBindVertexArray vao
 
@@ -55,11 +86,25 @@ type ShadedObjectContext =
         0
       glEnableVertexAttribArray 0u
 
+      match textureId with
+      | 0u ->
+          // TODO: This is not binding properly. Create a new buffer just for texture coordinates and bind it
+          glVertexAttribPointer
+            1u
+            2u
+            GL_FLOAT
+            false
+            2
+            4
+          glEnableVertexAttribArray 1u
+      | _ -> ()
+
       { VAO = vao
         VBO = vbo
         EBO = ebo
         Vertices = vertices
-        Indices = indices }
+        Indices = indices
+        Texture = textureId }
 
     static member UpdateIndices (indices) (context: ShadedObjectContext) : ShadedObjectContext =
       glBindBuffer
@@ -85,6 +130,8 @@ type ShadedObjectContext =
       { context with
           Vertices = vertices }
 
+    // TODO: Allow for dynamic update of texture
+
     static member Update (vertices) (indices) (context: ShadedObjectContext) : ShadedObjectContext =
       ShadedObjectContext.UpdateVertices vertices context
         |> ShadedObjectContext.UpdateIndices indices
@@ -108,13 +155,14 @@ type ShadedObject =
         else
           None
 
-  static member CreateQuad vertexPaths fragmentPaths transform width height =
+  static member CreateQuad vertexPaths fragmentPaths transform width height texture =
     match (
       Display.compileShader
         vertexPaths
         fragmentPaths
     ) with
     | Some shader ->
+        // TODO: Construct tex coords
         let vertices = [|
           // bottom left
           -width / 2.0f; -height / 2.0f; 0.0f;
@@ -130,7 +178,7 @@ type ShadedObject =
           1u; 2u; 3u; // second triangle vertex order as array indices
         |]
         Quad(
-          ShadedObjectContext.From vertices indices,
+          ShadedObjectContext.From vertices indices texture,
           shader,
           transform,
           width,
@@ -160,6 +208,8 @@ type ShadedObject =
         height
       )
 
+  // TODO: Allow for dynamic update of texture
+
   static member Update (vertices) (indices) (primitive: ShadedObject) : ShadedObject =
     match primitive with
     | Quad(context, shader, transform, width, height) -> Quad(
@@ -184,7 +234,7 @@ type ShadedObject =
 
     let mvp = modelMatrix * viewMatrix * projectionMatrix
     glUniformMatrix4fv mvpUniform 1 mvp
-    
+
     List.map
       (
         fun uniformData ->
@@ -261,12 +311,24 @@ type ShadedObject =
               | 3 -> glUniform3ui location data[0] data[1] data[2]
               | 4 -> glUniform4ui location data[0] data[1] data[2] data[3]
               | len -> fail $"Unsupported UVectorUniform length {len} when trying to use shader"
+          | SamplerUniform(name, data) ->
+              let location = glGetUniformLocation shader.Id name
+              glUniform1i location data
       )
       uniforms |> ignore
 
   static member Draw<'T> (config:Config<'T>) (viewMatrix:System.Numerics.Matrix4x4) (projectionMatrix:System.Numerics.Matrix4x4) (primitive:ShadedObject) (uniforms) =
     match primitive with
     | Quad(context, shader, transform, width, height) ->
+      let all_uniforms = 
+        match context.Texture with
+        | 0u -> uniforms
+        | _ -> [
+          SamplerUniform(
+            "in_texture",
+            0
+          )
+        ] @ uniforms
       ShadedObject.UseMvpShader
         config
         shader
@@ -286,8 +348,13 @@ type ShadedObject =
                 config.DisplayConfig.Height |> single
               )
             );
-          ] @ uniforms )
-
+          ] @ all_uniforms )
+
+      match context.Texture with
+      | 0u -> ()
+      | _ ->
+        glActiveTexture GL_TEXTURE0
+        glBindTexture GL_TEXTURE_2D context.Texture
       glBindVertexArray context.VAO
       glBindBuffer
         GL_ELEMENT_ARRAY_BUFFER

src/Womb/Graphics/Types.fs

@@ -1,7 +1,12 @@
 module Womb.Graphics.Types
 
+#nowarn "9" // unverifiable IL due to NativePtr library usage
+
+open Microsoft.FSharp.NativeInterop
+
 open SDL2Bindings
 open Womb.Lib.Types
+open Womb.Logging
 
 type DisplayConfig =
   { Width: uint;
@@ -48,3 +53,31 @@ type Uniform =
   | UVector3Uniform of Name:string * Data:UVector3
   | UVector4Uniform of Name:string * Data:UVector4
   | UVectorUniform of Name:string * Data:array<uint>
+  | SamplerUniform of Name:string * Data:IVector1
+
+type Texture2D = 
+  { Surface: option<nativeptr<SDL.SDL_Surface>>;
+    Width: int;
+    Height: int;
+    Data: voidptr;
+    Format: nativeint; }
+
+    static member Default() =
+      { Surface = None
+        Width = 0
+        Height = 0
+        Data = 0n.ToPointer()
+        Format = 0n }
+
+    static member FromPath path =
+      let surfacePtr = Image.IMG_Load(path)
+      if NativePtr.isNullPtr  surfacePtr then
+        fail $"Failed to load surface from path - {path}"
+        Texture2D.Default()
+      else
+        let surface = NativePtr.get surfacePtr 0
+        { Surface = Some surfacePtr
+          Width = surface.w
+          Height = surface.h
+          Data = surface.pixels.ToPointer()
+          Format = surface.format }