oglplus/020_cube_mapping.cpp

Shows how to draw an object with cube mapped surface

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/spiral_sphere.hpp>
#include <oglplus/images/newton.hpp>

#include <cmath>

#include "example.hpp"

namespace oglplus {

class CubeMapExample : public Example
{
private:
    // helper object building shape vertex attributes
    shapes::SpiralSphere make_shape;
    // helper object encapsulating shape drawing instructions
    shapes::DrawingInstructions shape_instr;
    // indices pointing to shape primitive elements
    shapes::SpiralSphere::IndexArray shape_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 shape
    VertexArray shape;

    // VBOs for the shape's vertex attributes
    Buffer verts, normals;

    // The environment cube map
    Texture tex;
public:
    CubeMapExample(void)
     : shape_instr(make_shape.Instructions())
     , shape_indices(make_shape.Indices())
     , projection_matrix(prog, "ProjectionMatrix")
     , camera_matrix(prog, "CameraMatrix")
     , model_matrix(prog, "ModelMatrix")
    {
        // Set the vertex shader source
        vs.Source(
            "#version 330\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "in vec2 TexCoord;"
            "out vec3 vertNormal;"
            "out vec3 vertLightDir;"
            "out vec3 vertLightRefl;"
            "out vec3 vertViewDir;"
            "out vec3 vertViewRefl;"
            "uniform vec3 LightPos;"
            "void main(void)"
            "{"
            "   gl_Position = ModelMatrix * Position;"
            "   vertNormal = mat3(ModelMatrix)*Normal;"
            "   vertLightDir = LightPos - gl_Position.xyz;"
            "   vertLightRefl = reflect("
            "       -normalize(vertLightDir),"
            "       normalize(vertNormal)"
            "   );"
            "   vertViewDir = ("
            "       vec4(0.0, 0.0, 1.0, 1.0)*"
            "       CameraMatrix"
            "   ).xyz;"
            "   vertViewRefl = reflect("
            "       normalize(vertViewDir),"
            "       normalize(vertNormal)"
            "   );"
            "   gl_Position = ProjectionMatrix * CameraMatrix * gl_Position;"
            "}"
        );
        // compile it
        vs.Compile();

        // set the fragment shader source
        fs.Source(
            "#version 330\n"
            "uniform samplerCube TexUnit;"
            "in vec3 vertNormal;"
            "in vec3 vertLightDir;"
            "in vec3 vertLightRefl;"
            "in vec3 vertViewDir;"
            "in vec3 vertViewRefl;"
            "out vec4 fragColor;"
            "void main(void)"
            "{"
            "   float l = length(vertLightDir);"
            "   float d = dot("
            "       normalize(vertNormal), "
            "       normalize(vertLightDir)"
            "   ) / l;"
            "   float s = dot("
            "       normalize(vertLightRefl),"
            "       normalize(vertViewDir)"
            "   );"
            "   vec3 lt = vec3(1.0, 1.0, 1.0);"
            "   vec3 env = texture(TexUnit, vertViewRefl).rgb;"
            "   fragColor = vec4("
            "       env * 0.4 + "
            "       (lt + env) * 1.5 * max(d, 0.0) + "
            "       lt * pow(max(s, 0.0), 64), "
            "       1.0"
            "   );"
            "}"
        );
        // 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 shape
        shape.Bind();

        verts.Bind(Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_shape.Positions(data);
            Buffer::Data(Buffer::Target::Array, data);
            VertexArrayAttrib attr(prog, "Position");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

        normals.Bind(Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_shape.Normals(data);
            Buffer::Data(Buffer::Target::Array, data);
            VertexArrayAttrib attr(prog, "Normal");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

        // setup the texture
        {
            GLuint tex_side = 256;
            auto image = images::NewtonFractal(
                tex_side, tex_side,
                Vec3f(0.3f, 0.1f, 0.2f),
                Vec3f(1.0f, 0.8f, 0.9f),
                Vec2f(-1.0f, -1.0f),
                Vec2f( 1.0f,  1.0f),
                images::NewtonFractal::X4Minus1(),
                images::NewtonFractal::DefaultMixer()
            );
            auto tex_target = Texture::Target::CubeMap;
            // texture syntax sugar
            tex << tex_target;
            tex_target << TextureMinFilter::Linear;
            tex_target << TextureMagFilter::Linear;
            tex_target << TextureWrap::ClampToEdge;

            for(int i=0; i!=6; ++i)
            {
                Texture::CubeMapFace(i) << image;
            }
        }
        // typechecked uniform with the exact sampler type
        Typechecked<Uniform<SLtoCpp<SLDataType::SamplerCube>>>(prog, "TexUnit").Set(0);

        //
        Uniform<Vec3f>(prog, "LightPos").Set(Vec3f(3.0f, 5.0f, 4.0f));
        //
        gl.ClearColor(0.2f, 0.05f, 0.1f, 0.0f);
        gl.ClearDepth(1.0f);
        gl.Enable(Capability::DepthTest);

        gl.Enable(Capability::CullFace);
        gl.FrontFace(make_shape.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, 100
            )
        );
    }

    void Render(double time)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        // set the matrix for camera orbiting the origin
        camera_matrix.Set(
            CamMatrixf::Orbiting(
                Vec3f(),
                4.5 - SineWave(time / 16.0) * 2.0,
                FullCircles(time / 12.0),
                Degrees(SineWave(time / 30.0) * 90)
            )
        );

        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationA(
                Vec3f(1.0f, 1.0f, 1.0f),
                FullCircles(time / 10.0)
            )
        );

        shape.Bind();
        shape_instr.Draw(shape_indices);
    }

    bool Continue(double time)
    {
        return time < 60.0;
    }
};

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 CubeMapExample);
}

} // namespace oglplus