oglplus/017_phong_torus.cpp

Shows how to draw a "phong"-like 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/twisted_torus.hpp>

#include <cmath>

#include "example.hpp"

namespace oglplus {

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

    // wrapper around the current OpenGL context
    Context gl;

    // Vertex shader
    VertexShader vs;

    // Fragment shader
    FragmentShader fs;

    // Program
    Program prog;

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

    // VBOs for the torus's vertex positions, normals and colors
    Buffer positions, normals, colors;
public:
    TorusExample(void)
     : make_torus()
     , torus_instr(make_torus.Instructions())
     , torus_indices(make_torus.Indices())
    {
        // Set the vertex shader source
        vs.Source(
            "#version 330\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "in vec3 Color;"
            "out vec3 vertColor;"
            "out vec3 vertNormal;"
            "out vec3 vertViewDir;"
            "void main(void)"
            "{"
            "   vertColor = normalize(vec3(1,1,1)-Color);"
            "   vertNormal = Normal;"
            "   vertViewDir = ("
            "       vec4(0.0, 0.0, 1.0, 1.0)*"
            "       CameraMatrix"
            "   ).xyz;"
            "   gl_Position = "
            "       ProjectionMatrix *"
            "       CameraMatrix *"
            "       Position;"
            "}"
        );
        // compile it
        vs.Compile();

        // set the fragment shader source
        fs.Source(
            "#version 330\n"
            "in vec3 vertColor;"
            "in vec3 vertNormal;"
            "in vec3 vertViewDir;"
            "out vec4 fragColor;"
            "uniform vec3 LightPos[3];"
            "void main(void)"
            "{"
            "   float amb = 0.2;"
            "   float diff = 0.0;"
            "   float spec = 0.0;"
            "   for(int i=0;i!=3;++i)"
            "   {"
            "       diff += max("
            "           dot(vertNormal,  LightPos[i])/"
            "           dot(LightPos[i], LightPos[i]),"
            "           0.0"
            "       );"
            "       float k = dot(vertNormal, LightPos[i]);"
            "       vec3 r = 2.0*k*vertNormal - LightPos[i];"
            "       spec += pow(max("
            "           dot(normalize(r), vertViewDir),"
            "           0.0"
            "       ), 32.0 * dot(r, r));"
            "   }"
            "   fragColor = "
            "       vec4(vertColor, 1.0)*(amb+diff)+"
            "       vec4(1.0, 1.0, 1.0, 1.0)*spec;"
            "}"
        );
        // compile it
        fs.Compile();

        // attach the shaders to the program
        prog.AttachShader(vs);
        prog.AttachShader(fs);
        // link and use it
        prog.Link();
        prog.Use();

        // bind the VAO for the torus
        torus.Bind();

        // bind the VBO for the torus vertex positions
        positions.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
            VertexArrayAttrib attr(prog, "Position");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.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
            VertexArrayAttrib attr(prog, "Normal");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

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

        // set the light positions
        Uniform<Vec3f> light_pos(prog, "LightPos");
        light_pos[0].Set(Vec3f(2.0f,-1.0f, 0.0f));
        light_pos[1].Set(Vec3f(0.0f, 3.0f,-1.0f));
        light_pos[2].Set(Vec3f(0.0f,-1.0f, 4.0f));
        //
        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);
    }

    void Reshape(GLuint width, GLuint height)
    {
        gl.Viewport(width, height);
        prog.Use();
        Uniform<Mat4f>(prog, "ProjectionMatrix").Set(
            CamMatrixf::PerspectiveX(
                Degrees(60),
                double(width)/height,
                1, 30
            )
        );
    }

    void Render(double time)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        // set the matrix for camera orbiting the origin
        Uniform<Mat4f>(prog, "CameraMatrix").Set(
            CamMatrixf::Orbiting(
                Vec3f(),
                5.0,
                FullCircles(time / 17.0),
                Degrees(SineWave(time / 19.0) * 90)
            )
        );

        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