GLScene/Examples/Demos/materials/multipass/fMultipassC.cpp

//---------------------------------------------------------------------------
/*: Simple TGLShader based multipass demo.

   This demo uses a custom TGLShader subclass to implement the classic
   multipass hidden lines rendering technique on a torus: first pass renders
   model with filled triangles, second pass does the wireframe.

   You'll also note the glPolygonOffset call, it displaces fragments depths
   value a little "farther away" so that surface fill depth values do not
   interact with the rendering of the lines (comment out the call and you'll
   see).
   The axis and sphere allow you to see the limit of that simple technique:
   it actually "paints" between the lines, so you cannot use it to make
   transparent wireframed objects with hidden lines - if that thought ever
   blossomed in your mind ;)

   Additionnal objects around the show a glow/toon edges effect achieved in two
   passes too: the 1st pass activate lines and gives them a width, the second
   is used to fill the surface (and clear the lines that aren't on edges).
   (TOutLineShader thanks to Delauney Jerome, [email protected])
*/
#include <vcl.h>
#pragma hdrstop

#include "fMultipassC.h"
#include <assert.h>

//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma link "GLS.GeomObjects"
#pragma link "GLS.Objects"
#pragma link "GLS.Scene"
#pragma link "GLS.Texture"
#pragma link "GLS.SceneViewer"
#pragma link "GLS.BaseClasses"
#pragma link "GLS.Coordinates"

#pragma link "GLS.Material"
#pragma link "Stage.OpenGLTokens"

#pragma resource "*.dfm"
TForm1* Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) {}
//---------------------------------------------------------------------------
__fastcall THiddenLineShader::THiddenLineShader(TComponent* AOwner) :
    TGLShader(AOwner)
{
}
//---------------------------------------------------------------------------
__fastcall THiddenLineShader::~THiddenLineShader(void) {}
//---------------------------------------------------------------------------
void __fastcall THiddenLineShader::DoApply(
    TGLRenderContextInfo &rci, System::TObject* Sender)
{
    // new object getting rendered, 1st pass
    PassCount = 1;

    // backup state
    glPushAttrib(GL_ENABLE_BIT);
    // disable lighting, this is a solid fill
    glDisable(GL_LIGHTING);
    rci.GLStates->PolygonMode = GL_FRONT_AND_BACK, GL_FILL;
    // use background color
    glColor3fv(&BackgroundColor.X);
    // enable and adjust polygon offset
    glEnable(GL_POLYGON_OFFSET_FILL);
    glPolygonOffset(1, 2);
}
//---------------------------------------------------------------------------
bool __fastcall THiddenLineShader::DoUnApply(TGLRenderContextInfo &rci)
{
    bool result;

    switch (PassCount) {
        case 1: {
            // 1st pass completed, we setup for the second
            PassCount = 2;

            // switch to wireframe and its color
            rci.GLStates->PolygonMode = GL_FRONT_AND_BACK, GL_LINE;
            glColor3fv(&LineColor.X);
            // disable polygon offset
			glDisable(GL_POLYGON_OFFSET_LINE);

            result = true;
            break;
        }
        case 2: {
            // restore state
            glPopAttrib();

            // we're done
            result = false;
            break;
        }
        default: {
            // doesn't hurt to be cautious
            assert(false);
            result = false;
        }
    }
    return result;
}
//---------------------------------------------------------------------------
__fastcall TOutLineShader::TOutLineShader(TComponent* AOwner) :
    TGLShader(AOwner)
{
}
//---------------------------------------------------------------------------
__fastcall TOutLineShader::~TOutLineShader(void) {}
//---------------------------------------------------------------------------
void __fastcall TOutLineShader::DoApply(
    TGLRenderContextInfo &rci, System::TObject* Sender)
{
	PassCount = 1;
    glPushAttrib(GL_ENABLE_BIT);
    glDisable(GL_LIGHTING);

    if (OutlineSmooth) {
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
        glEnable(GL_LINE_SMOOTH);
    } else
        glDisable(GL_LINE_SMOOTH);

    glGetFloatv(GL_LINE_WIDTH, &OldlineWidth);
    glLineWidth(OutlineWidth);
    glPolygonMode(GL_BACK, GL_LINE);
    glCullFace(GL_FRONT);
    glDepthFunc(GL_LEQUAL);
    glColor3fv(&LineColor.X);
}
//---------------------------------------------------------------------------
bool __fastcall TOutLineShader::DoUnApply(TGLRenderContextInfo &rci)
{
    bool result;

    switch (PassCount) {
        case 1: {
            PassCount = 2;
            if (Lighting)
                glEnable(GL_LIGHTING);
            else
                glColor3fv(&BackgroundColor.X);
            glDepthFunc(GL_LESS);
			glCullFace(GL_BACK);
            glPolygonMode(GL_BACK, GL_FILL);

            result = true;
            break;
        }
        case 2: {
            glPopAttrib();
            glLineWidth(OldlineWidth);
            result = false;
            break;
        }
        default: {
            assert(false);
            result = false;
        }
    }
    return result;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::BUBindClick(TObject* Sender)
{
    THiddenLineShader* shader1;
    TOutLineShader *shader2, *shader3;

    BUBind->Enabled = False;

    // instantiate our shaders

    shader1 = new THiddenLineShader(this);
    shader1->BackgroundColor =
        ConvertWinColor(GLSceneViewer1->Buffer->BackgroundColor, 0);
	shader1->LineColor = clrBlue;

    shader2 = new TOutLineShader(this);

    shader2->BackgroundColor =
        ConvertWinColor(GLSceneViewer1->Buffer->BackgroundColor, 0);
    shader2->OutlineSmooth = true;
    shader2->OutlineWidth = 2;
    shader2->Lighting = false;
    shader2->LineColor = clrBlack;

    shader3 = new TOutLineShader(this);
    shader3->BackgroundColor =
        ConvertWinColor(GLSceneViewer1->Buffer->BackgroundColor, 0);
    shader3->OutlineSmooth = false;
    shader3->OutlineWidth = 4;
    shader3->Lighting = true;
    shader3->LineColor = clrRed;

    // binds the shaders to the materials
    GLMaterialLibrary1->Materials->Items[0]->Shader = shader1;
    GLMaterialLibrary1->Materials->Items[1]->Shader = shader2;
    GLMaterialLibrary1->Materials->Items[2]->Shader = shader3;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::GLSceneViewer1MouseDown(
    TObject* Sender, TMouseButton Button, TShiftState Shift, int X, int Y)
{
    mx = X;
    my = Y;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::GLSceneViewer1MouseMove(
    TObject* Sender, TShiftState Shift, int X, int Y)
{
    if (Shift.Contains(ssLeft))
        GLCamera1->MoveAroundTarget(my - Y, mx - X);
    else if (Shift.Contains(ssRight))
        GLCamera1->RotateTarget(my - Y, mx - X, 0);
    mx = X;
    my = Y;
}
//---------------------------------------------------------------------------