92 lines
2.6 KiB
Standard ML
92 lines
2.6 KiB
Standard ML
structure GlDraw =
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struct
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(* The name doesn't make it clear, but this structure
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* couples GLFW and OpenGL.
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* I'm not sure if I will use native windowing systems
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* or other graphics APIs at a later stage,
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* but the current priority is GLFW + OpenGL.
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* *)
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type t =
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{ textVertexBuffer: Word32.word
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, textProgram: Word32.word
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, textDrawLength: int
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, window: MLton.Pointer.t
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}
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fun createShader (shaderType, shaderString) =
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let
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val shader = Gles3.createShader shaderType
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val _ = Gles3.shaderSource (shader, shaderString)
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val _ = Gles3.compileShader shader
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in
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shader
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end
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fun createProgram (vertexShader, fragmentShader) =
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let
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val program = Gles3.createProgram ()
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val _ = Gles3.attachShader (program, vertexShader)
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val _ = Gles3.attachShader (program, fragmentShader)
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val _ = Gles3.linkProgram program
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in
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program
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end
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fun create window =
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let
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(* create vertex buffer, program, etc. for text. *)
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val textVertexBuffer = Gles3.createBuffer ()
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val xyrgbVertexShader = createShader
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(Gles3.VERTEX_SHADER, GlShaders.xyrgbVertexShaderString)
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val rgbFragmentShader = createShader
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(Gles3.FRAGMENT_SHADER, GlShaders.rgbFragmentShaderString)
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val textProgram = createProgram (xyrgbVertexShader, rgbFragmentShader)
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(* clean up shaders which are no longer needed once progran is linked. *)
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val _ = Gles3.deleteShader xyrgbVertexShader
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val _ = Gles3.deleteShader rgbFragmentShader
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in
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{ textVertexBuffer = textVertexBuffer
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, textProgram = textProgram
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, textDrawLength = 0
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, window = window
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}
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end
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fun uploadText ({textVertexBuffer, ...}: t, vec) =
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let
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val _ = Gles3.bindBuffer textVertexBuffer
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val _ = Gles3.bufferData (vec, Vector.length vec, Gles3.STATIC_DRAW)
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in
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()
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end
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fun drawText ({textVertexBuffer, textProgram, textDrawLength, ...}: t) =
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if textDrawLength > 0 then
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let
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val _ = Gles3.bindBuffer textVertexBuffer
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(* enable xy component from uploaded array *)
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val _ = Gles3.vertexAttribPointer (0, 2, 5, 0)
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val _ = Gles3.enableVertexAttribArray 0
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(* enable rgb component from uploaded array *)
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val _ = Gles3.vertexAttribPointer (1, 3, 5, 8)
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val _ = Gles3.enableVertexAttribArray 1
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val _ = Gles3.useProgram textProgram
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val _ = Gles3.drawArrays (Gles3.TRIANGLES, 0, textDrawLength)
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in
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()
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end
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else
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()
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fun draw (drawObject: t) =
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let
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val _ = drawText drawObject
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in
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()
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end
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end
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