DefaultShaders.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include "opengl-precomp.h"  // Precompiled header
//
#include <mrpt/opengl/DefaultShaders.h>
#include <mrpt/opengl/opengl_api.h>


using namespace mrpt::opengl;

// TODO: May be, allow users to register custom shaders?

Program::Ptr mrpt::opengl::LoadDefaultShader(const shader_id_t id)
{
#if MRPT_HAS_OPENGL_GLUT

#if defined(MRPT_OS_LINUX)
    // Workaround to enfore wxWidgets to use GLSL>=3.3 even for wxWidgets<3.0.4
    // See CWxGLCanvasBase::CWxGLCanvasBase.
    if (!::getenv("MESA_GL_VERSION_OVERRIDE"))
    {
        std::string s = "MESA_GL_VERSION_OVERRIDE=3.3";
        ::putenv(s.data());
    }
#endif

    // Vertex shader:
    const char* vertex_shader = nullptr;
    const char* fragment_shader = nullptr;
    std::vector<std::string> attribs, uniforms;

    switch (id)
    {
        case DefaultShaderID::POINTS:
            vertex_shader =
#include "../shaders/points.v.glsl"
                ;
            fragment_shader =
#include "../shaders/points.f.glsl"
                ;
            uniforms = {
                "p_matrix",
                "mv_matrix",
                "vertexPointSize",
                "enableVariablePointSize",
                "variablePointSize_K",
                "variablePointSize_DepthScale"};
            attribs = {"position", "vertexColor"};
            break;

            // ==============================
        case DefaultShaderID::WIREFRAME:
            vertex_shader =
#include "../shaders/wireframe.v.glsl"
                ;
            fragment_shader =
#include "../shaders/wireframe.f.glsl"
                ;
            uniforms = {"p_matrix", "mv_matrix"};
            attribs = {"position", "vertexColor"};
            break;

            // ==============================
        case DefaultShaderID::TRIANGLES:
            vertex_shader =
#include "../shaders/triangles.v.glsl"
                ;
            fragment_shader =
#include "../shaders/triangles.f.glsl"
                ;
            uniforms = {"p_matrix",      "mv_matrix",      "light_diffuse",
                        "light_ambient", "light_specular", "light_direction"};
            attribs = {"position", "vertexColor", "vertexNormal"};
            break;
            // ==============================
        case DefaultShaderID::TEXTURED_TRIANGLES:
            vertex_shader =
#include "../shaders/textured-triangles.v.glsl"
                ;
            fragment_shader =
#include "../shaders/textured-triangles.f.glsl"
                ;
            uniforms = {"p_matrix",        "mv_matrix",      "pmv_matrix",
                        "light_diffuse",   "light_ambient",  "light_specular",
                        "light_direction", "textureSampler", "enableLight"};
            attribs = {"position", "vertexUV", "vertexNormal"};
            break;
            // ==============================
        case DefaultShaderID::TEXT:
            vertex_shader =
#include "../shaders/text.v.glsl"
                ;
            fragment_shader =
#include "../shaders/text.f.glsl"
                ;
            uniforms = {"p_matrix", "mv_matrix"};
            attribs = {"position", "vertexColor"};
            break;

        default:
            THROW_EXCEPTION_FMT(
                "Unknown shader_id_t=%u", static_cast<unsigned>(id));
    };

            // Init GLEW if not already done:
#ifdef _WIN32
    glewInit();
#endif

    auto shader = std::make_shared<Program>();

    std::string errMsgs;
    std::vector<Shader> lstShaders;
    lstShaders.resize(2);
    if (!lstShaders[0].compile(GL_VERTEX_SHADER, vertex_shader, errMsgs))
    {
        THROW_EXCEPTION_FMT(
            "Error compiling GL_VERTEX_SHADER:\n%s", errMsgs.c_str());
    }
    if (!lstShaders[1].compile(GL_FRAGMENT_SHADER, fragment_shader, errMsgs))
    {
        THROW_EXCEPTION_FMT(
            "Error compiling GL_FRAGMENT_SHADER:\n%s", errMsgs.c_str());
    }
    if (!shader->linkProgram(lstShaders, errMsgs))
    {
        THROW_EXCEPTION_FMT(
            "Error linking Opengl Shader programs:\n%s", errMsgs.c_str());
    }

#if 0
    // Debug:
    std::cout << "Built Shader program #" << int(id) << "\n";
    shader->dumpProgramDescription(std::cout);
    std::cout << "\n";
#endif

    // Uniforms:
    for (const auto& name : uniforms) shader->declareUniform(name);

    // Attributes:
    for (const auto& name : attribs) shader->declareAttribute(name);

    return shader;
#else
    THROW_EXCEPTION("MRPT built without OpenGL support.");
#endif
}