oglplus/016_noise_torus.cpp

Shows how to draw a torus with a grayscale noise texture

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 <oglplus/bound/texture.hpp>
#include <oglplus/bound/buffer.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 vertex attributes
    Buffer verts, normals, texcoords;

    // texture for the torus
    DefaultTexture tex;
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;"
            "in vec2 TexCoord;"
            "out vec3 vertNormal;"
            "out vec3 vertLight;"
            "out vec2 vertTexCoord;"
            "uniform vec3 LightPos;"
            "void main(void)"
            "{"
            "   gl_Position = ModelMatrix * Position;"
            "   vertNormal = mat3(ModelMatrix)*Normal;"
            "   vertLight = LightPos - gl_Position.xyz;"
            "   vertTexCoord = TexCoord;"
            "   gl_Position = ProjectionMatrix * CameraMatrix * gl_Position;"
            "}"
        ).Compile();

        // set the fragment shader source and compile it
        fs.Source(
            "#version 330\n"
            "uniform sampler2D TexUnit;"
            "in vec3 vertNormal;"
            "in vec3 vertLight;"
            "in vec2 vertTexCoord;"
            "out vec4 fragColor;"
            "void main(void)"
            "{"
            "   float l = sqrt(length(vertLight));"
            "   float d = l > 0? dot("
            "       vertNormal, "
            "       normalize(vertLight)"
            "   ) / l : 0.0;"
            "   float i = 0.2 + 3.2*max(d, 0.0);"
            "   fragColor = texture(TexUnit, vertTexCoord)*i;"
            "}"
        ).Compile();

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

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

        // bind the VBO for the torus vertices
        gl.Bind(Buffer::Target::Array, verts);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_torus.Positions(data);
            // upload the data
            gl.Current(Buffer::Target::Array).Data(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
        gl.Bind(Buffer::Target::Array, normals);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_torus.Normals(data);
            // upload the data
            gl.Current(Buffer::Target::Array).Data(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 texture coordinates
        gl.Bind(Buffer::Target::Array, texcoords);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_torus.TexCoordinates(data);
            // upload the data
            gl.Current(Buffer::Target::Array).Data(data);
            // setup the vertex attribs array for the vertices
            VertexArrayAttrib attr(prog, "TexCoord");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

        // setup the texture
        gl.Bind(Texture::Target::_2D, tex);
        {
            GLuint s = 256;
            std::vector<GLubyte> tex_data(s*s);
            for(GLuint v=0;v!=s;++v)
            {
                for(GLuint u=0;u!=s;++u)
                {
                    tex_data[v*s+u] = rand() % 0x100;
                }
            }
            gl.Current(Texture::Target::_2D)
                .MinFilter(TextureMinFilter::Linear)
                .MagFilter(TextureMagFilter::Linear)
                .WrapS(TextureWrap::Repeat)
                .WrapT(TextureWrap::Repeat)
                .SwizzleG(TextureSwizzle::Red)
                .SwizzleB(TextureSwizzle::Red)
                .Image2D(
                    0,
                    PixelDataInternalFormat::Red,
                    s, s,
                    0,
                    PixelDataFormat::Red,
                    PixelDataType::UnsignedByte,
                    tex_data.data()
                );
        }
        // typechecked uniform with exact data type
        Typechecked<Uniform<SLtoCpp<SLDataType::Sampler2D>>>(prog, "TexUnit").Set(0);
        //
        Uniform<Vec3f>(prog, "LightPos").Set(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);
    }

    void Reshape(GLuint width, GLuint height)
    {
        gl.Viewport(width, height);
        prog.Use();
        projection_matrix.Set(
            CamMatrixf::PerspectiveX(
                Degrees(60),
                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(),
                4.5,
                Degrees(time * 35),
                Degrees(SineWave(time / 20.0) * 60)
            )
        );
        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationX(FullCircles(time * 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