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/* Shader.cpp
Copyright (c) 2014 by Michael Zahniser
Endless Sky is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later version.
Endless Sky is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "Shader.h"
#include "../Logger.h"
#include <cctype>
#include <cstring>
#include <stdexcept>
#include <string>
#include <vector>
using namespace std;
void Shader::Load(const char *vertex, const char *fragment)
{
GLuint vertexShader = Compile(vertex, GL_VERTEX_SHADER);
GLuint fragmentShader = Compile(fragment, GL_FRAGMENT_SHADER);
program = glCreateProgram();
if(!program)
throw runtime_error("Creating OpenGL shader program failed.");
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
glLinkProgram(program);
glDetachShader(program, vertexShader);
glDetachShader(program, fragmentShader);
GLint status;
glGetProgramiv(program, GL_LINK_STATUS, &status);
if(status == GL_FALSE)
{
GLint maxLength = 0;
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &maxLength);
vector<GLchar> infoLog(maxLength);
glGetProgramInfoLog(program, maxLength, &maxLength, &infoLog[0]);
string error(infoLog.data());
Logger::LogError(error);
throw runtime_error("Linking OpenGL shader program failed.");
}
}
GLuint Shader::Object() const noexcept
{
return program;
}
GLint Shader::Attrib(const char *name) const
{
GLint attrib = glGetAttribLocation(program, name);
if(attrib == -1)
throw runtime_error("Attribute \"" + string(name) + "\" not found.");
return attrib;
}
GLint Shader::Uniform(const char *name) const
{
GLint uniform = glGetUniformLocation(program, name);
if(uniform == -1)
throw runtime_error("Uniform \"" + string(name) + "\" not found.");
return uniform;
}
GLuint Shader::Compile(const char *str, GLenum type)
{
GLuint object = glCreateShader(type);
if(!object)
throw runtime_error("Shader creation failed.");
static string version;
if(version.empty())
{
version = "#version ";
string glsl = reinterpret_cast<const char *>(glGetString(GL_SHADING_LANGUAGE_VERSION));
bool found = false;
for(char c : glsl)
{
if(!found && !isdigit(c))
{
continue;
}
if(isspace(c))
break;
if(isdigit(c))
{
found = true;
version += c;
}
}
if(glsl.find("GLSL ES") != std::string::npos)
{
version += " es";
}
version += '\n';
}
size_t length = strlen(str);
vector<GLchar> text(version.length() + length + 1);
memcpy(&text.front(), version.data(), version.length());
memcpy(&text.front() + version.length(), str, length);
text[version.length() + length] = '\0';
const GLchar *cText = &text.front();
glShaderSource(object, 1, &cText, nullptr);
glCompileShader(object);
GLint status;
glGetShaderiv(object, GL_COMPILE_STATUS, &status);
if(status == GL_FALSE)
{
string error = version;
error += string(str, length);
static const int SIZE = 4096;
GLchar message[SIZE];
GLsizei length;
glGetShaderInfoLog(object, SIZE, &length, message);
error += string(message, length);
Logger::LogError(error);
throw runtime_error("Shader compilation failed.");
}
return object;
}
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