OpenSubdiv/examples/common/glUtils.cpp

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//
// Copyright 2015 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
// names, trademarks, service marks, or product names of the Licensor
// and its affiliates, except as required to comply with Section 4(c) of
// the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#include <sstream>
#include <string>
#include "glUtils.h"
namespace GLUtils {
void
CheckGLErrors(std::string const & where) {
GLuint err;
while ((err = glGetError()) != GL_NO_ERROR) {
std::cerr << "GL error: "
<< (where.empty() ? "" : where + " ")
<< err << "\n";
}
}
GLuint
CompileShader(GLenum shaderType, const char *source) {
GLuint shader = glCreateShader(shaderType);
glShaderSource(shader, 1, &source, NULL);
glCompileShader(shader);
GLint status;
glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE) {
GLchar emsg[40960];
glGetShaderInfoLog(shader, sizeof(emsg), 0, emsg);
fprintf(stderr, "Error compiling GLSL shader: %s\n", emsg);
return 0;
}
return shader;
}
bool
SupportsAdaptiveTessellation() {
#ifdef OSD_USES_GLEW
// XXXtakahito:
// glewGetExtension doesn't work if the context is initialized
// with core profile, since glGetStrings(GL_EXTENSIONS) return
// NULL.
//
//return glewGetExtension("GL_ARB_tessellation_shader") != NULL;
2015-05-26 22:33:05 +00:00
return glewIsSupported("GL_ARB_tessellation_shader") == GL_TRUE;
#else
#if defined(GL_ARB_tessellation_shader) || defined(GL_VERSION_4_0)
return true;
#else
return false;
#endif
#endif
}
///Helper function that parses the open gl version string, retrieving the major
///and minor version from it.
void GetMajorMinorVersion(int *major, int *minor){
static bool initialized = false;
int _major = -1, _minor = -1;
if (!initialized || _major == -1 || _minor == -1){
const GLubyte *ver = glGetString(GL_SHADING_LANGUAGE_VERSION);
if (!ver){
_major = -1;
_minor = -1;
}
else{
std::string major_str(ver, ver + 1);
std::string minor_str(ver + 2, ver + 3);
std::stringstream ss;
ss << major_str << " " << minor_str;
ss >> _major;
ss >> _minor;
}
initialized = true;
}
*major = _major;
*minor = _minor;
}
/** Gets the shader version based on the current opengl version and returns
* it in a string form */
const std::string &GetShaderVersion(){
static bool initialized = false;
static std::string shader_version;
if (!initialized){
int major, minor;
GetMajorMinorVersion(&major, &minor);
int version_number = major * 10 + minor;
switch (version_number){
case 20:
shader_version = "110";
break;
case 21:
shader_version = "120";
break;
case 30:
shader_version = "130";
break;
case 31:
shader_version = "140";
break;
case 32:
shader_version = "150";
break;
default:
std::stringstream ss;
ss << version_number;
shader_version = ss.str() + "0";
break;
}
initialized = true;
}
return shader_version;
}
/* Generates the version defintion needed by the glsl shaders based on the
* opengl string
*/
const std::string &GetShaderVersionInclude(){
static bool initialized = false;
static std::string include;
if (!initialized){
include = "#version " + GetShaderVersion() + "\n";
initialized = true;
}
return include;
}
bool GL_ARBSeparateShaderObjectsOrGL_VERSION_4_1(){
#if defined(OSD_USES_GLEW)
bool initialized = false, uses = false;
if (!initialized){
uses = glewGetExtension("GL_ARB_separate_shader_objects") ||
(GLEW_VERSION_4_1
&& glewGetExtension("GL_ARB_tessellation_shader"));
initialized = true;
}
return uses;
#else
#if defined(GL_ARB_separate_shader_objects) || defined(GL_VERSION_4_1)
return true;
#else
return false;
#endif
#endif
}
bool GL_ARBComputeShaderOrGL_VERSION_4_3() {
#if defined(OSD_USES_GLEW)
return (glewIsSupported("GL_ARB_compute_shader") == GL_TRUE) ||
(GLEW_VERSION_4_3);
#else
#if defined(GL_ARB_compute_shader) || defined(GL_VERSION_4_3)
return true;
#else
return false;
#endif
#endif
}
} // namesapce GLUtils