GLUtil.cc

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#include "GLUtil.hh"
 
#include "File.hh"
#include "FileContext.hh"
#include "FileException.hh"
#include "InitException.hh"
 
#include "Version.hh"
 
#include <bit>
#include <cstdio>
#include <iostream>
 
using namespace openmsx;
 
namespace gl {
 
void checkGLError(std::string_view prefix)
{
        GLenum error = glGetError();
        if (error != GL_NO_ERROR) {
                // TODO this needs glu, but atm we don't link against glu (in windows)
                //std::string err = (const char*)gluErrorString(error);
                std::cerr << "GL error: " << prefix << ": " << int(error) << '\n';
                assert(false);
        }
}
 
 
// class Texture
 
Texture::Texture(bool interpolation, bool wrap)
{
        allocate();
        setInterpolation(interpolation);
        setWrapMode(wrap);
}
 
void Texture::allocate()
{
        glGenTextures(1, &textureId);
}
 
void Texture::reset()
{
        // Calling glDeleteTextures with a 0-texture-id is OK, it doesn't do
        // anything. So from that point of view we don't need this test. However
        // during initialization, before the openGL context is created, we
        // already create some Texture(null) objects. These can also be moved
        // around (std::move()), and then when the moved-from object gets
        // deleted that also calls this method. That should be fine as calling
        // glDeleteTextures() with 0 does nothing. EXCEPT that on macOS it does
        // crash when calling an openGL function before an openGL context is
        // created (it works fine on Linux and Windows).
        if (textureId) {
                glDeleteTextures(1, &textureId);
                textureId = 0;
        }
}
 
void Texture::setInterpolation(bool interpolation)
{
        bind();
        int mode = interpolation ? GL_LINEAR : GL_NEAREST;
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, mode);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mode);
}
 
void Texture::setWrapMode(bool wrap)
{
        bind();
        int mode = wrap ? GL_REPEAT : GL_CLAMP_TO_EDGE;
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, mode);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, mode);
}
 
 
// class ColorTexture
 
ColorTexture::ColorTexture(GLsizei width_, GLsizei height_)
{
        resize(width_, height_);
}
 
void ColorTexture::resize(GLsizei width_, GLsizei height_)
{
        width = width_;
        height = height_;
        bind();
        glTexImage2D(
                GL_TEXTURE_2D,    // target
                0,                // level
                GL_RGBA,          // internal format
                width,            // width
                height,           // height
                0,                // border
                GL_RGBA,          // format
                GL_UNSIGNED_BYTE, // type
                nullptr);         // data
}
 
 
// class FrameBufferObject
 
FrameBufferObject::FrameBufferObject(Texture& texture)
{
        glGenFramebuffers(1, &bufferId);
        push();
        glFramebufferTexture2D(GL_FRAMEBUFFER,
                               GL_COLOR_ATTACHMENT0,
                               GL_TEXTURE_2D, texture.textureId, 0);
        bool success = glCheckFramebufferStatus(GL_FRAMEBUFFER) ==
                       GL_FRAMEBUFFER_COMPLETE;
        pop();
        if (!success) {
                throw InitException(
                        "Your OpenGL implementation support for "
                        "framebuffer objects is too limited.");
        }
}
 
FrameBufferObject::~FrameBufferObject()
{
        pop();
        glDeleteFramebuffers(1, &bufferId);
}
 
void FrameBufferObject::push()
{
        glGetIntegerv(GL_FRAMEBUFFER_BINDING, &previousId);
        glBindFramebuffer(GL_FRAMEBUFFER, bufferId);
}
 
void FrameBufferObject::pop()
{
        glBindFramebuffer(GL_FRAMEBUFFER, GLuint(previousId));
}
 
 
// class Shader
 
void Shader::init(GLenum type, std::string_view header, std::string_view filename)
{
        // Load shader source.
        std::string source;
        if constexpr (OPENGL_VERSION == OPENGL_ES_2_0) {
                source += "#version 100\n";
                if (type == GL_FRAGMENT_SHADER) {
                        source += "#ifdef GL_FRAGMENT_PRECISION_HIGH\n"
                                "  precision highp float;\n"
                                "#else\n"
                                "  precision mediump float;\n"
                                "#endif\n";
                }
        } else {
                source += "#version 110\n";
        }
        source += header;
        try {
                File file(systemFileContext().resolve(tmpStrCat("shaders/", filename)));
                auto mmap = file.mmap();
                source.append(std::bit_cast<const char*>(mmap.data()),
                              mmap.size());
        } catch (FileException& e) {
                std::cerr << "Cannot find shader: " << e.getMessage() << '\n';
                handle = 0;
                return;
        }
 
        // Allocate shader handle.
        handle = glCreateShader(type);
        if (handle == 0) {
                std::cerr << "Failed to allocate shader\n";
                return;
        }
 
        // Set shader source.
        const char* sourcePtr = source.c_str();
        glShaderSource(handle, 1, &sourcePtr, nullptr);
 
        // Compile shader and print any errors and warnings.
        glCompileShader(handle);
        const bool ok = isOK();
        GLint infoLogLength = 0;
        glGetShaderiv(handle, GL_INFO_LOG_LENGTH, &infoLogLength);
        // note: the null terminator is included, so empty string has length 1
        if (!ok || (!Version::RELEASE && infoLogLength > 1)) {
                std::string infoLog(infoLogLength - 1, '\0');
                glGetShaderInfoLog(handle, infoLogLength, nullptr, infoLog.data());
                std::cerr << (ok ? "Warning" : "Error") << "(s) compiling shader \""
                          << filename << "\":\n"
                          << (infoLogLength > 1 ? infoLog.data() : "(no details available)\n");
        }
}
 
Shader::~Shader()
{
        glDeleteShader(handle); // ok to delete '0'
}
 
bool Shader::isOK() const
{
        if (handle == 0) return false;
        GLint compileStatus = GL_FALSE;
        glGetShaderiv(handle, GL_COMPILE_STATUS, &compileStatus);
        return compileStatus == GL_TRUE;
}
 
 
// class ShaderProgram
 
void ShaderProgram::allocate()
{
        handle = glCreateProgram();
        if (handle == 0) {
                std::cerr << "Failed to allocate program\n";
        }
}
 
void ShaderProgram::reset()
{
        // ok to delete '0', but see comment in Texture::reset()
        if (handle) {
                glDeleteProgram(handle);
                handle = 0;
        }
}
 
bool ShaderProgram::isOK() const
{
        if (handle == 0) return false;
        GLint linkStatus = GL_FALSE;
        glGetProgramiv(handle, GL_LINK_STATUS, &linkStatus);
        return linkStatus == GL_TRUE;
}
 
void ShaderProgram::attach(const Shader& shader)
{
        // Sanity check on this program.
        if (handle == 0) return;
 
        // Sanity check on the shader.
        if (!shader.isOK()) return;
 
        // Attach it.
        glAttachShader(handle, shader.handle);
}
 
void ShaderProgram::link()
{
        // Sanity check on this program.
        if (handle == 0) return;
 
        // Link the program and print any errors and warnings.
        glLinkProgram(handle);
        const bool ok = isOK();
        GLint infoLogLength = 0;
        glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &infoLogLength);
        // note: the null terminator is included, so empty string has length 1
        if (!ok || (!Version::RELEASE && infoLogLength > 1)) {
                std::string infoLog(infoLogLength - 1, '\0');
                glGetProgramInfoLog(handle, infoLogLength, nullptr, infoLog.data());
                fprintf(stderr, "%s(s) linking shader program:\n%s\n",
                        ok ? "Warning" : "Error",
                        infoLogLength > 1 ? infoLog.data() : "(no details available)\n");
        }
}
 
void ShaderProgram::bindAttribLocation(unsigned index, const char* name)
{
        glBindAttribLocation(handle, index, name);
}
 
GLint ShaderProgram::getUniformLocation(const char* name) const
{
        // Sanity check on this program.
        if (!isOK()) return -1;
 
        return glGetUniformLocation(handle, name);
}
 
void ShaderProgram::activate() const
{
        glUseProgram(handle);
}
 
// only useful for debugging
void ShaderProgram::validate() const
{
        glValidateProgram(handle);
        GLint validateStatus = GL_FALSE;
        glGetProgramiv(handle, GL_VALIDATE_STATUS, &validateStatus);
        GLint infoLogLength = 0;
        glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &infoLogLength);
        // note: the null terminator is included, so empty string has length 1
        std::string infoLog(infoLogLength - 1, '\0');
        glGetProgramInfoLog(handle, infoLogLength, nullptr, infoLog.data());
        std::cout << "Validate "
                  << ((validateStatus == GL_TRUE) ? "OK" : "FAIL")
                  << ": " << infoLog.data() << '\n';
}
 
 
// class BufferObject
 
BufferObject::BufferObject()
{
        glGenBuffers(1, &bufferId);
}
 
BufferObject::~BufferObject()
{
        glDeleteBuffers(1, &bufferId); // ok to delete 0-buffer
}
 
} // namespace gl