oglplus/022_parallax_map.cpp

Shows how to achieve a simple view parallax effect on a checker cube

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/cube.hpp>
#include <oglplus/images/sphere_bmap.hpp>
#include <oglplus/bound/buffer.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;

    static Program make(void)
    {
        Shader vs(ShaderType::Vertex);
        vs.Source(
            "#version 330\n"
            "uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
            "uniform vec3 LightPos;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "in vec3 Tangent;"
            "in vec2 TexCoord;"
            "out vec3 vertEye;"
            "out vec3 vertLight;"
            "out vec3 vertNormal;"
            "out vec2 vertTexCoord;"
            "out vec3 vertViewTangent;"
            "out mat3 NormalMatrix;"
            "void main(void)"
            "{"
            "   vec4 EyePos = "
            "       CameraMatrix *"
            "       ModelMatrix *"
            "       Position;"
            "   vertEye = EyePos.xyz;"
            "   vec3 fragTangent = ("
            "       CameraMatrix *"
            "       ModelMatrix *"
            "       vec4(Tangent, 0.0)"
            "   ).xyz;"
            "   vertNormal = ("
            "       CameraMatrix *"
            "       ModelMatrix *"
            "       vec4(Normal, 0.0)"
            "   ).xyz;"
            "   vertLight = ("
            "       CameraMatrix *"
            "       vec4(LightPos-vertEye, 1.0)"
            "   ).xyz;"
            "   NormalMatrix = mat3("
            "       fragTangent,"
            "       cross(vertNormal, fragTangent),"
            "       vertNormal"
            "   );"
            "   vertViewTangent = vec3("
            "       dot(NormalMatrix[0], vertEye),"
            "       dot(NormalMatrix[1], vertEye),"
            "       dot(NormalMatrix[2], vertEye) "
            "   );"
            "   vertTexCoord = TexCoord;"
            "   gl_Position = ProjectionMatrix *"
            "       EyePos;"
            "}"
        ).Compile();

        Shader fs(ShaderType::Fragment);
        fs.Source(
            "#version 330\n"
            "uniform sampler2D BumpTex;"
            "uniform int BumpTexWidth;"
            "uniform int BumpTexHeight;"
            "float DepthMult = 0.1;"
            "in vec3 vertEye;"
            "in vec3 vertLight;"
            "in vec3 vertNormal;"
            "in vec2 vertTexCoord;"
            "in vec3 vertViewTangent;"
            "in mat3 NormalMatrix;"
            "out vec4 fragColor;"
            "void main(void)"
            "{"
            "   vec3 ViewTangent = normalize(vertViewTangent);"
            "   float perp = -dot(normalize(vertEye), vertNormal);"
            "   float sampleInterval = 1.0/length("
            "       vec2(BumpTexWidth, BumpTexHeight)"
            "   );"
            "   vec3 sampleStep = ViewTangent*sampleInterval;"
            "   float prevD = 0.0;"
            "   float depth = texture(BumpTex, vertTexCoord).w;"
            "   float maxOffs = min((depth*DepthMult)/(-ViewTangent.z), 1.0);"
            "   vec3 viewOffs = vec3(0.0, 0.0, 0.0);"
            "   vec2 offsTexC = vertTexCoord + viewOffs.xy;"
            "   while(length(viewOffs) < maxOffs)"
            "   {"
            "       if(offsTexC.x <= 0.0 || offsTexC.x >= 1.0)"
            "           break;"
            "       if(offsTexC.y <= 0.0 || offsTexC.y >= 1.0)"
            "           break;"
            "       if(depth*DepthMult*perp <= -viewOffs.z)"
            "           break;"
            "       viewOffs += sampleStep;"
            "       offsTexC = vertTexCoord + viewOffs.xy;"
            "       prevD = depth;"
            "       depth = texture(BumpTex, offsTexC).w;"
            "   }"
            "   offsTexC = vec2("
            "       clamp(offsTexC.x, 0.0, 1.0),"
            "       clamp(offsTexC.y, 0.0, 1.0) "
            "   );"
            "   float b = ("
            "       1 +"
            "       int(offsTexC.x*16) % 2+"
            "       int(offsTexC.y*16) % 2"
            "   ) % 2;"
            "   vec3 c = vec3(b, b, b);"
            "   vec3 n = texture(BumpTex, offsTexC).xyz;"
            "   vec3 finalNormal = NormalMatrix * n;"
            "   float l = length(vertLight);"
            "   float d = (l > 0.0) ? dot("
            "       normalize(vertLight), "
            "       finalNormal"
            "   ) / l : 0.0;"
            "   float i = 0.1 + 2.5*max(d, 0.0);"
            "   fragColor = vec4(c*i, 1.0);"
            "}"
        ).Compile();

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

        return prog;
    }

    // Uniforms
    Uniform<Mat4f> projection_matrix, camera_matrix, model_matrix;
    Uniform<Vec3f> light_pos;

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

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

    // The bumpmap texture
    Texture bumpTex;
public:
    CubeExample(void)
     : cube_instr(make_cube.Instructions())
     , cube_indices(make_cube.Indices())
     , prog(make())
     , projection_matrix(prog, "ProjectionMatrix")
     , camera_matrix(prog, "CameraMatrix")
     , model_matrix(prog, "ModelMatrix")
     , light_pos(prog, "LightPos")
    {
        // bind the VAO for the cube
        gl.Bind(cube);

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

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

        gl.Bind(Buffer::Target::Array, tangents);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_cube.Tangents(data);
            Buffer::Data(Buffer::Target::Array, data);
            (prog|"Tangent").Setup<GLfloat>(n_per_vertex).Enable();
        }

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

        {
            auto img = images::SphereBumpMap(512, 512, 2, 2);
            Uniform<GLint>(prog, "BumpTexWidth").Set(img.Width());
            Uniform<GLint>(prog, "BumpTexHeight").Set(img.Height());
            UniformSampler(prog, "BumpTex").Set(0);
            Texture::Active(0);

            gl.Bound(Texture::Target::_2D, bumpTex)
                .MinFilter(TextureMinFilter::LinearMipmapLinear)
                .MagFilter(TextureMagFilter::Linear)
                .WrapS(TextureWrap::Repeat)
                .WrapT(TextureWrap::Repeat)
                .Image2D(img)
                .GenerateMipmap();
        }
        //
        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_cube.FaceWinding());
    }

    void Reshape(GLuint width, GLuint height)
    {
        gl.Viewport(width, height);
        prog.Use();
        projection_matrix.Set(
            CamMatrixf::PerspectiveX(
                Degrees(54),
                double(width)/height,
                1, 10
            )
        );
    }

    void Render(double time)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        auto lightAzimuth = FullCircles(time * -0.5);
        light_pos.Set(
            Vec3f(
                -Cos(lightAzimuth),
                1.0f,
                -Sin(lightAzimuth)
            ) * 2.0f
        );
        //
        camera_matrix.Set(
            CamMatrixf::Orbiting(
                Vec3f(),
                3.0f,
                Degrees(-45),
                Degrees(SineWave(time / 30.0) * 70)
            )
        );

        // set the model matrix
        model_matrix.Set(
            ModelMatrixf::RotationA(
                Vec3f(1.0f, 1.0f, 1.0f),
                FullCircles(-time * 0.05)
            )
        );

        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