oglplus/016_metallic_torus.cpp

Shows how to draw a metallic-looking torus

Copyright 2008-2014 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;

    // Vertex shader
    VertexShader vs;

    // Fragment shader
    FragmentShader fs;

    // Program
    Program prog;

    // Uniforms
    Lazy<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())
     , projection_matrix(prog, "ProjectionMatrix")
     , camera_matrix(prog, "CameraMatrix")
     , model_matrix(prog, "ModelMatrix")
    {
        // Set the vertex shader source and compile it
        vs.Source(
            "#version 330\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "out vec3 vertNormal;"
            "void main(void)"
            "{"
            "   vertNormal = mat3(CameraMatrix)*mat3(ModelMatrix)*Normal;"
            "   gl_Position = "
            "       ProjectionMatrix *"
            "       CameraMatrix *"
            "       ModelMatrix *"
            "       Position;"
            "}"
        ).Compile();

        // set the fragment shader source and compile it
        fs.Source(
            "#version 330\n"
            "uniform int ColorCount;"
            "uniform vec4 Color[8];"
            "in vec3 vertNormal;"
            "vec3 ViewDir = vec3(0.0, 0.0, 1.0);"
            "vec3 TopDir = vec3(0.0, 1.0, 0.0);"
            "out vec4 fragColor;"
            "void main(void)"
            "{"
            "   float k = dot(vertNormal, ViewDir);"
            "   vec3 reflDir = 2.0*k*vertNormal - ViewDir;"
            "   float a = dot(reflDir, TopDir);"
            "   vec3 reflColor;"
            "   for(int i = 0; i != (ColorCount - 1); ++i)"
            "   {"
            "       if(a<Color[i].a && a>=Color[i+1].a)"
            "       {"
            "           float m = "
            "               (a - Color[i].a)/"
            "               (Color[i+1].a-Color[i].a);"
            "           reflColor = mix("
            "               Color[i].rgb,"
            "               Color[i+1].rgb,"
            "               m"
            "           );"
            "           break;"
            "       }"
            "   }"
            "   float i = max(dot(vertNormal, TopDir), 0.0);"
            "   vec3 diffColor = vec3(i, i, i);"
            "   fragColor = vec4("
            "       mix(reflColor, diffColor, 0.3 + i*0.7),"
            "       1.0"
            "   );"
            "}"
        ).Compile();

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

        // 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
            VertexArrayAttrib attr(prog, "Position");
            attr.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
            VertexArrayAttrib attr(prog, "Normal");
            attr.Setup<GLfloat>(n_per_vertex).Enable();
        }

        // setup the color gradient
        Uniform<GLint>(prog, "ColorCount").Set(8);
        Uniform<Vec4f> color(prog, "Color");
        color[0].Set(1.0f, 1.0f, 0.9f, 1.00f);
        color[1].Set(1.0f, 0.9f, 0.8f, 0.97f);
        color[2].Set(0.9f, 0.7f, 0.5f, 0.95f);
        color[3].Set(0.5f, 0.5f, 1.0f, 0.95f);
        color[4].Set(0.2f, 0.2f, 0.7f, 0.00f);
        color[5].Set(0.1f, 0.1f, 0.1f, 0.00f);
        color[6].Set(0.2f, 0.2f, 0.2f,-0.10f);
        color[7].Set(0.5f, 0.5f, 0.5f,-1.00f);

        gl.ClearColor(0.1f, 0.1f, 0.1f, 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();
        projection_matrix.Set(
            CamMatrixf::PerspectiveX(
                Degrees(80),
                double(width)/height,
                1, 20
            )
        );
    }

    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 / 60.0) * 80)
            )
        );
        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationX(FullCircles(time * 0.25))
        );

        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