oglplus/016_textured_cube_glsl120.cpp

Shows how to draw a simple textured cube (using GLSL 120)

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/opt/smart_enums.hpp>
#include <oglplus/shapes/cube.hpp>
#include <oglplus/images/newton.hpp>
#include <oglplus/bound/texture.hpp>

#include <cmath>

#include "example.hpp"

namespace oglplus {

class CubeExample : public Example
{
private:
    // helper object building cube vertex attributes
    shapes::Cube make_cube;
    // helper object encapsulating cube drawing instructions
    shapes::DrawingInstructions cube_instr;
    // indices pointing to cube primitive elements
    shapes::Cube::IndexArray cube_indices;

    // wrapper around the current OpenGL context
    Context gl;

    // Program
    Program prog;

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

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

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

    // The stained glass texture
    Texture tex;
public:
    CubeExample(void)
     : cube_instr(make_cube.Instructions())
     , cube_indices(make_cube.Indices())
     , projection_matrix(prog, "ProjectionMatrix")
     , camera_matrix(prog, "CameraMatrix")
     , model_matrix(prog, "ModelMatrix")
    {
        namespace se = oglplus::smart_enums;
        VertexShader vs;
        vs.Source(
            "#version 120\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
            "attribute vec4 Position;"
            "attribute vec3 Normal;"
            "attribute vec2 TexCoord;"
            "varying vec3 vertNormal;"
            "varying vec3 vertLight;"
            "varying vec2 vertTexCoord;"
            "uniform vec3 LightPos;"
            "void main(void)"
            "{"
            "   vertNormal = mat3(ModelMatrix)*Normal;"
            "   gl_Position = ModelMatrix * Position;"
            "   vertLight = LightPos - gl_Position.xyz;"
            "   vertTexCoord = TexCoord;"
            "   gl_Position = ProjectionMatrix * CameraMatrix * gl_Position;"
            "}"
        ).Compile();

        FragmentShader fs;
        fs.Source(
            "#version 120\n"
            "uniform sampler2D TexUnit;"
            "varying vec3 vertNormal;"
            "varying vec3 vertLight;"
            "varying vec2 vertTexCoord;"
            "void main(void)"
            "{"
            "   float l = length(vertLight);"
            "   float d = l > 0 ? dot(vertNormal, normalize(vertLight)) / l : 0.0;"
            "   float i = 0.3 + 2.0*max(d, 0.0);"
            "   vec4 t = texture2D(TexUnit, vertTexCoord);"
            "   gl_FragColor = vec4(t.rgb*i, 1.0);"
            "}"
        ).Compile();

        prog.AttachShader(vs).AttachShader(fs).Link().Use();

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

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

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

        texcoords.Bind(se::Array());
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_cube.TexCoordinates(data);
            Buffer::Data(se::Array(), data);
            (prog|"TexCoord").Setup<GLfloat>(n_per_vertex).Enable();
        }

        // setup the texture
        {
            auto image = images::NewtonFractal(
                512, 512,
                Vec3f(1.0f, 1.4f, 1.3f),
                Vec3f(0.2f, 0.3f, 0.1f),
                Vec2f(-1.0f, -1.0f),
                Vec2f( 1.0f,  1.0f),
                images::NewtonFractal::X4Minus1(),
                [](double x) -> double
                {
                    return pow(SineWave(pow(x,0.5)), 4.0);
                }
            );
            gl.Bound(se::_2D(), tex)
                .MinFilter(se::LinearMipmapLinear())
                .MagFilter(se::Linear())
                .WrapS(se::Repeat())
                .WrapT(se::Repeat())
                .Image2D(image)
                .GenerateMipmap();
        }
        // set the uniform values
        (prog/"TexUnit") = 0;
        (prog/"LightPos") = Vec3f(1.0f, 2.0f, 3.0f);
        //
        gl.ClearColor(0.1f, 0.1f, 0.1f, 0.0f);
        gl.ClearDepth(1.0f);
        gl.Enable(se::DepthTest());

        gl.Enable(se::CullFace());
        gl.FrontFace(make_cube.FaceWinding());
    }

    void Reshape(GLuint width, GLuint height)
    {
        gl.Viewport(width, height);
        prog.Use();
        projection_matrix.Set(
            CamMatrixf::PerspectiveX(
                Degrees(60),
                GLfloat(width)/height,
                0.1, 30
            )
        );
    }

    void Render(double time)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        // set the matrix for camera orbiting the origin
        camera_matrix.Set(
            CamMatrixf::Orbiting(
                Vec3f(),
                7.5 - SineWave(time / 6.0) * 6.0,
                FullCircles(time * 0.03),
                Degrees(SineWave(time / 30.0) * 90)
            )
        );

        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationX(FullCircles(time * 0.01))
        );

        cube.Bind();
        gl.CullFace(Face::Back);
        cube_instr.Draw(cube_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 CubeExample);
}

} // namespace oglplus