基于opengl编写一个简易的2d渲染框架-13使用例子

void init(Pass*& p1, Pass*& p2)
{
    p1 = new Pass;
    p2 = new Pass;

    Shader* s1 = new Shader("Shader/defaultGeometryShader.vs", "Shader/defaultGeometryShader.frag", CVA_V3F_C4F);
    Shader* s2 = new Shader("Shader/defaultGeometryShader.vs", "Shader/defaultGeometryShader.frag", CVA_V3F_C4F);

    p1->enableBlend(true);
    p2->enableBlend(true);

    p1->setBlendFunc(BLEND_SRC_ALPHA, BLEND_ONE_MINUS_SRC_ALPHA, BLEND_ONE, BLEND_ZERO);
    p2->setBlendFunc(BLEND_SRC_ALPHA, BLEND_ONE_MINUS_SRC_ALPHA, BLEND_ONE, BLEND_ZERO);

    p1->setShader(s1);
    p2->setShader(s2);

    p1->setPrimType(PT_TRIANGLES);
    p2->setPrimType(PT_TRIANGLES);

    p1->enableStencilTest(true);
    p1->setStencilMask(0xFF);
    p1->setStencilCompareFunc(COMPARE_ALWAYS);
    p1->setStencilRef(1);
    p1->setStencilOp(STENCIL_OP_KEEP, STENCIL_OP_KEEP, STENCIL_OP_REPLACE);

    p2->enableStencilTest(true);
    p2->setStencilMask(0xFF);
    p2->setStencilCompareFunc(COMPARE_EQUAL);
    p2->setStencilRef(1);
    p2->setStencilOp(STENCIL_OP_KEEP, STENCIL_OP_KEEP, STENCIL_OP_REPLACE);
}

/* 模板测试 */
void stencilTest(GraphicsContext* gc, Canvas2D* canvas, Pass* p1, Pass* p2)
{
    static float d = 0;
    static float d1 = 0;
    static float h = 0;

    Vec2 vs1[23];
    Vec2 vs2[23];

    gc->render();
    canvas->setCustomPass(p1);
    canvas->fillCircle(Vec3(400, 300, 0), 100, 360, Color(1, 1, 1, 0));
    gc->render();

    canvas->setCustomPass(p2);

    float hz = 20;
    vs1[0].set(500, 200);
    vs1[1].set(300, 200);
    for ( int i = 0; i <= hz; i++ ) {
        float y = sinf(i / hz * PI_2 + d + i / hz * 2);

        vs1[i + 2].set(300 + i / hz * 200, y * 15 + 200 + h);
    }
    canvas->fillPath(vs1, 23, Color(0, 1, 0, 0.5));

    
    vs2[0].set(500, 200);
    vs2[1].set(300, 200);
    for ( int i = 0; i <= hz; i++ ) {
        float y = sinf(i / hz * PI_2 + d1 + i / hz * 3);

        vs2[i + 2].set(300 + i / hz * 200, y * (10 + i / hz * 10) + 200 + h);
    }
    canvas->fillPath(vs2, 23, Color(0, 1, 0, 0.7));

    gc->render();
    canvas->setCustomPass(nullptr);

    h += 0.08;
    if ( h > 200 ) {
        h = 0;
    }

    d += 0.01;
    if ( d >= PI_2 ) d = 0;
    d1 += 0.02;
    if ( d1 >= PI_2 ) d1 = 0;
}

    ParticleSystem* ball = new ParticleSystem();
    ball->initWithPlist("Particle/motion.plist");
    ball->setTexture("Particle/fire.png");
    ball->getEmitter()->setEmitPos(Vec2(400, 300));

    Pass* pass = ball->getPass();
    pass->enableScissor(true);
    pass->setScissorRect(100, 100, 600, 400);

    ParticleSystemManager manager;
    manager.appendParticleSystem(ball);

/* 裁剪测试 */
void scissorTest(ParticleSystem* ps, Canvas2D* canvas)
{
    static float x = 400, y = 300;
    static int xdir = 1, ydir = 1;
    static float clipx1 = 0, clipy1 = 0, clipx2 = 800, clipy2 = 600;
    static int clipdx = 1, clipdy = 1;

    ps->getEmitter()->setEmitPos(Vec2(x, y));
    int speed = 2.5;
    x -= xdir * speed;
    y -= ydir * speed;
    if ( x < 0 ) {
        xdir = -1;
    }
    else if ( x > DEFAULT_WIN_W ) {
        xdir = 1;
    }
    if ( y < 0 ) {
        ydir = -1;
    }
    else if ( y > DEFAULT_WIN_H ) {
        ydir = 1;
    }

    clipx1 += clipdx * 0.5f;
    clipx2 -= clipdx * 0.5f;
    clipy1 += clipdy * 0.5f;
    clipy2 -= clipdy * 0.5f;
    if ( clipx1 >= 150 ) {
        clipdx = -1;
    }
    else if ( clipx1 <= 0 ) {
        clipdx = 1;
    }
    if ( clipy1 >= 150 ) {
        clipdy = -1;
    }
    else if ( clipy1 <= 0 ) {
        clipdy = 1;
    }
    canvas->drawLine(0, clipy1, DEFAULT_WIN_W, clipy1, Color(0, 1, 0, 1));
    canvas->drawLine(clipx1, 0, clipx1, DEFAULT_WIN_H, Color(0, 1, 0, 1));

    canvas->drawLine(0, clipy2, DEFAULT_WIN_W, clipy2, Color(0, 1, 0, 1));
    canvas->drawLine(clipx2, 0, clipx2, DEFAULT_WIN_H, Color(0, 1, 0, 1));
    ps->getPass()->setScissorRect(clipx1, clipy1, clipx2 - clipx1, clipy2 - clipy1);
}

        for ( int i = 0; i < 10; i++ ) {
            int x = 20 + i * 20;
            int y = 20 + i * 20;
            if ( i < 5 ) {
                canvas.fillRect(x, y, x + 100, y + 100, Color(0.2 * i, 0, 0, 0.1 + 0.1 * i), i);
            }
            else {
                canvas.fillRect(x, y, x + 100, y + 100, Color(0, 0, 0.2 * i, 0.1 * i), i);
            }
        }