oglplus/016_cartoon_torus.cpp

Shows how to draw a cartoon-like cel shaded torus

Copyright 2008-2013 Matus Chochlik. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <oglplus/gl.hpp>
#include <oglplus/all.hpp>
#include <oglplus/shapes/torus.hpp>

#include <cmath>

#include "example.hpp"

namespace oglplus {

class TorusExample : public Example
{
private:
    // helper object building torus vertex attributes
    shapes::Torus make_torus;
    // helper object encapsulating torus drawing instructions
    shapes::DrawingInstructions torus_instr;
    // indices pointing to torus primitive elements
    shapes::Torus::IndexArray torus_indices;

    // wrapper around the current OpenGL context
    Context gl;

    // Program
    Program prog;
    static Program make_prog(void)
    {
        VertexShader vs;
        vs.Source(
            "#version 330\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "out vec3 vertNormal;"
            "void main(void)"
            "{"
            "   vertNormal = mat3(ModelMatrix)*Normal;"
            "   gl_Position = "
            "       ProjectionMatrix *"
            "       CameraMatrix *"
            "       ModelMatrix *"
            "       Position;"
            "}"
        ).Compile();

        FragmentShader fs;
        fs.Source(
            "#version 330\n"
            "in vec3 vertNormal;"
            "out vec4 fragColor;"
            "uniform vec3 LightPos;"
            "void main(void)"
            "{"
            "   float intensity = 2.0 * max("
            "       dot(vertNormal,  LightPos)/"
            "       length(LightPos),"
            "       0.0"
            "   );"
            "   if(!gl_FrontFacing)"
            "       fragColor = vec4(0.0, 0.0, 0.0, 1.0);"
            "   else if(intensity > 0.9)"
            "       fragColor = vec4(1.0, 0.9, 0.8, 1.0);"
            "   else if(intensity > 0.1)"
            "       fragColor = vec4(0.7, 0.6, 0.4, 1.0);"
            "   else"
            "       fragColor = vec4(0.3, 0.2, 0.1, 1.0);"
            "}"
        ).Compile();

        Program prog;
        prog << vs << fs;
        prog.Link().Use();
        return prog;
    }

    // Uniforms
    Uniform<Mat4f> projection_matrix, camera_matrix, model_matrix;

    // A vertex array object for the rendered torus
    VertexArray torus;

    // VBOs for the torus's vertices and normals
    Buffer verts, normals;
public:
    TorusExample(void)
     : make_torus(1.0, 0.5, 72, 48)
     , torus_instr(make_torus.Instructions())
     , torus_indices(make_torus.Indices())
     , prog(make_prog())
     , projection_matrix(prog, "ProjectionMatrix")
     , camera_matrix(prog, "CameraMatrix")
     , model_matrix(prog, "ModelMatrix")
    {
        // bind the VAO for the torus
        torus.Bind();

        // bind the VBO for the torus vertices
        verts.Bind(Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_torus.Positions(data);
            // upload the data
            Buffer::Data(Buffer::Target::Array, data);
            // setup the vertex attribs array for the vertices
            (prog|"Position").Setup<GLfloat>(n_per_vertex).Enable();
        }

        // bind the VBO for the torus normals
        normals.Bind(Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_torus.Normals(data);
            // upload the data
            Buffer::Data(Buffer::Target::Array, data);
            // setup the vertex attribs array for the vertices
            (prog|"Normal").Setup<GLfloat>(n_per_vertex).Enable();
        }
        //
        // set the light position
        (prog/"LightPos").Set(Vec3f(4.0f, 4.0f, -8.0f));

        gl.ClearColor(0.8f, 0.8f, 0.7f, 0.0f);
        gl.ClearDepth(1.0f);
        gl.Enable(Capability::DepthTest);
        gl.Enable(Capability::CullFace);
        gl.FrontFace(make_torus.FaceWinding());
        gl.CullFace(Face::Back);
        glLineWidth(4.0f);
    }

    void Reshape(GLuint width, GLuint height)
    {
        gl.Viewport(width, height);
        prog.Use();
        projection_matrix.Set(
            CamMatrixf::PerspectiveX(
                Degrees(75),
                double(width)/height,
                1, 30
            )
        );
    }

    void Render(double time)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        // set the matrix for camera orbiting the origin
        camera_matrix.Set(
            CamMatrixf::Orbiting(
                Vec3f(),
                3.5,
                Degrees(time * 35),
                Degrees(SineWave(time / 20.0) * 60)
            )
        );
        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationY(FullCircles(time * 0.25)) *
            ModelMatrixf::RotationX(FullCircles(0.25))
        );

        gl.PolygonMode(PolygonMode::Line);
        gl.CullFace(Face::Front);
        torus_instr.Draw(torus_indices);
        //
        gl.PolygonMode(PolygonMode::Fill);
        gl.CullFace(Face::Back);
        torus_instr.Draw(torus_indices);
    }

    bool Continue(double time)
    {
        return time < 30.0;
    }
};

void setupExample(ExampleParams& /*params*/){ }

std::unique_ptr<ExampleThread> makeExampleThread(
    Example& /*example*/,
    unsigned /*thread_id*/,
    const ExampleParams& /*params*/
){ return std::unique_ptr<ExampleThread>(); }

std::unique_ptr<Example> makeExample(const ExampleParams& /*params*/)
{
    return std::unique_ptr<Example>(new TorusExample);
}

} // namespace oglplus