LZScene

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//
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// This unit is part of the GLScene Engine https://github.com/glscene
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//
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{
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   Ivory shader simulate Ivory material.
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   At this time only one light source is supported
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    History :  
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     08/12/15 - J.Delauney - Creation
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}
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unit GLSLIvoryShader;
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interface
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{$I GLScene.inc}
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uses
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  Classes,
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  GLScene, GLCrossPlatform, GLBaseClasses, GLState, OpenGLTokens, OpenGL1x, GLContext, GLRenderContextInfo,
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  GLVectorGeometry, GLCoordinates,
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  GLTextureFormat,GLColor, GLTexture, GLMaterial,
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  GLSLShader, GLCustomShader;
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//TGLCustomGLSLIvoryShader
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//
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{ Custom class for GLSLIvoryShader.
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 A shader that simulate Ivory Material }
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type
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  TGLCustomGLSLIvoryShader = class(TGLCustomGLSLShader)
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  private
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  protected
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    procedure DoApply(var rci : TGLRenderContextInfo; Sender : TObject); override;
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    function DoUnApply(var rci: TGLRenderContextInfo): Boolean; override;
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  public
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    constructor Create(AOwner : TComponent); override;
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    destructor Destroy; override;
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  end;
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type
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  TGLSLIvoryShader = class(TGLCustomGLSLIvoryShader)
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  end;
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implementation
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{ TGLCustomGLSLIvoryShader }
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constructor TGLCustomGLSLIvoryShader.Create(AOwner: TComponent);
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begin
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  inherited;
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  with VertexProgram.Code do
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  begin
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    Clear;
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    Add('varying vec3 normal; ');
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    Add('varying vec3 lightVec; ');
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    Add('varying vec3 viewVec; ');
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    Add(' ');
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    Add('void main() ');
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    Add('{ ');
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    Add('  gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; ');
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    Add('  vec4 lightPos = gl_LightSource[0].position;');
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    Add('  vec4 vert =  gl_ModelViewMatrix * gl_Vertex; ');
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    Add('  normal = gl_NormalMatrix * gl_Normal; ');
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    Add('  lightVec = vec3(lightPos - vert); ');
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    Add('  viewVec = -vec3(vert); ');
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    Add('} ');
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  end;
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  with FragmentProgram.Code do
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  begin
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    Clear;
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    Add('varying vec3 normal; ');
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    Add('varying vec3 lightVec; ');
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    Add('varying vec3 viewVec; ');
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    Add(' ');
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    Add('void main() ');
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    Add('{ ');
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    Add('vec3 norm = normalize(normal); ');
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    Add('vec3 L = normalize(lightVec); ');
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    Add('vec3 V = normalize(viewVec); ');
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    Add('vec3 halfAngle = normalize(L + V); ');
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    Add('float NdotL = dot(L, norm); ');
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    Add('float NdotH = clamp(dot(halfAngle, norm), 0.0, 1.0); ');
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    Add('// "Half-Lambert" technique for more pleasing diffuse term ');
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    Add('float diffuse = 0.5 * NdotL + 0.5; ');
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    Add('float specular = pow(NdotH, 64.0); ');
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    Add('float result = diffuse + specular; ');
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    Add('gl_FragColor = vec4(result); ');
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    Add('} ');
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  end;
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  // Initial stuff.
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end;
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destructor TGLCustomGLSLIvoryShader.Destroy;
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begin
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  inherited;
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end;
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procedure TGLCustomGLSLIvoryShader.DoApply(var rci: TGLRenderContextInfo;
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  Sender: TObject);
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begin
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  GetGLSLProg.UseProgramObject;
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end;
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function TGLCustomGLSLIvoryShader.DoUnApply(
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  var rci: TGLRenderContextInfo): Boolean;
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begin
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  Result := False;
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  GetGLSLProg.EndUseProgramObject;
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end;
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end.
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