standalone/007_glm_boxes.cpp

Shows interoperability with GLM matrix and vector classesCopyright 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 "glut_glew_example.hpp"

#include <oglplus/all.hpp>
#include <oglplus/shapes/cube.hpp>

#define GLM_FORCE_RADIANS
#include <oglplus/interop/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>


class GLMBoxesExample
 : public oglplus::StandaloneExample
{
private:
    oglplus::shapes::Cube make_cube;
    oglplus::shapes::DrawingInstructions cube_instr;
    oglplus::shapes::Cube::IndexArray cube_indices;

    oglplus::Context gl;

    oglplus::VertexShader vs;
    oglplus::FragmentShader fs;
    oglplus::Program prog;

    oglplus::Lazy<oglplus::Uniform<float>> frame_time;

    oglplus::VertexArray cube;
    oglplus::Buffer positions, normals;
public:
    GLMBoxesExample(int, const char**)
     : cube_instr(make_cube.Instructions())
     , cube_indices(make_cube.Indices())
     , frame_time(prog, "Time")
    {
        // Set the vertex shader source
        vs.Source(
            "#version 330\n"
            "uniform mat4 CameraMatrix, ScaleMatrix;"
            "uniform vec3 LightPos;"
            "uniform float Time;"
            "in vec4 Position;"
            "in vec3 Normal;"
            "out vec3 vertColor;"
            "void main(void)"
            "{"
            "   float angle = gl_InstanceID * 10 * 2 * 3.14159 / 360.0;"
            "   float ct = cos(angle+Time);"
            "   float st = sin(angle+Time);"
            "   mat4 ModelMatrix = mat4("
            "        ct, 0.0,  st, 0.0,"
            "       0.0, 1.0, 0.0, 0.0,"
            "       -st, 0.0,  ct, 0.0,"
            "       0.0, 0.0, 0.0, 1.0 "
            "   ) * mat4("
            "        1.0, 0.0, 0.0, 0.0,"
            "        0.0, 1.0, 0.0, 0.0,"
            "        0.0, 0.0, 1.0, 0.0,"
            "       12.0, 0.0, 0.0, 1.0 "
            "   ) * mat4("
            "        ct, -st, 0.0, 0.0,"
            "        st,  ct, 0.0, 0.0,"
            "       0.0, 0.0, 1.0, 0.0,"
            "       0.0, 0.0, 0.0, 1.0 "
            "   );"
            "   gl_Position = "
            "       ModelMatrix *"
            "       ScaleMatrix *"
            "       Position;"

            "   vec3 vertLightDir = normalize(LightPos - gl_Position.xyz);"
            "   vec3 vertNormal = normalize(("
            "       ModelMatrix *"
            "       vec4(Normal, 0.0)"
            "   ).xyz);"

            "   gl_Position = CameraMatrix * gl_Position;"

            "   vertColor = abs(normalize("
            "       Normal -"
            "       vec3(1.0, 1.0, 1.0) +"
            "       Position.xyz*0.2"
            "   )) * (0.6 + 0.5*max(dot(vertNormal, vertLightDir), 0.0));"
            "}"
        );
        // compile it
        vs.Compile();

        // set the fragment shader source
        fs.Source(
            "#version 330\n"
            "in vec3 vertColor;"
            "out vec3 fragColor;"
            "void main(void)"
            "{"
            "   fragColor = vertColor;"
            "}"
        );
        // 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 cube
        cube.Bind();

        // bind the VBO for the cube vertex positions
        positions.Bind(oglplus::Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_cube.Positions(data);
            // upload the data
            oglplus::Buffer::Data(oglplus::Buffer::Target::Array, data);
            // setup the vertex attribs array for the vertices
            oglplus::VertexArrayAttrib attr(prog, "Position");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

        // bind the VBO for the cube normals
        normals.Bind(oglplus::Buffer::Target::Array);
        {
            std::vector<GLfloat> data;
            GLuint n_per_vertex = make_cube.Normals(data);
            // upload the data
            oglplus::Buffer::Data(oglplus::Buffer::Target::Array, data);
            // setup the vertex attribs array for the vertices
            oglplus::VertexArrayAttrib attr(prog, "Normal");
            attr.Setup<GLfloat>(n_per_vertex);
            attr.Enable();
        }

        //
        gl.ClearColor(0.8f, 0.8f, 0.8f, 0.0f);
        gl.ClearDepth(1.0f);
        gl.Enable(oglplus::Capability::DepthTest);

        oglplus::Typechecked<oglplus::Uniform<glm::vec3>>(prog, "LightPos").Set(
            glm::vec3(7.0, 3.0, -1.0)
        );

        oglplus::Typechecked<oglplus::Uniform<glm::mat4x4>>(prog, "ScaleMatrix").Set(
            glm::scale(glm::mat4(1.0), glm::vec3(1.0, 0.3, 1.7))
        );
    }

    void Reshape(void)
    {
        gl.Viewport(Width(), Height());

        auto camera = glm::perspective(
            53.0f*3.1415f/180.f,
            GLfloat(Aspect()),
            1.0f, 100.0f
        ) * glm::lookAt(
            glm::vec3(21.0f, 7.0f, 0.0f),
            glm::vec3( 0.0f, 0.0f, 0.0f),
            glm::vec3( 0.0f, 1.0f, 0.0f)
        );
        oglplus::Uniform<glm::mat4x4>(prog, "CameraMatrix").Set(camera);
    }

    void Render(void)
    {
        gl.Clear().ColorBuffer().DepthBuffer();
        //
        frame_time.Set(FrameTime());

        // draw 36 instances of the cube
        // the vertex shader will take care of their placement
        cube_instr.Draw(cube_indices, 36);
    }
};

int main(int argc, char* argv[])
{
    return oglplus::GlutGlewMain<GLMBoxesExample>(
        "Example usage with GLM matrix and vector classes",
        argc, argv
    );
}