QgOval::QgOval(QgPoint pOrig, double a, double b, QgColor c)
:QgLines()
{
std::vector<QgPoint> points;
MakePoints(points, pOrig, a, b, 0, 2 * QG_PI);
AddPoints(points);
SetColor(c);
}
static void
Init(void)
{
static const char *fragShaderText =
"uniform float StipplePattern[16]; \n"
"varying vec2 stippleCoord; \n"
"void main() \n"
"{ \n"
" // check the stipple pattern and discard if value is zero \n"
" // TODO: we should really undo the perspective interpolation here \n"
" // so that it's linear. \n"
" float stip = StipplePattern[int(fract(stippleCoord.x) * 16.0)]; \n"
" if (stip == 0.0) \n"
" discard; \n"
" gl_FragColor = gl_Color; \n"
"} \n";
static const char *vertShaderText =
"void main() \n"
"{ \n"
" gl_FrontColor = gl_Color; \n"
" gl_Position = ftransform(); \n"
"} \n";
static const char *geomShaderText =
"#version 150 \n"
"#extension GL_ARB_geometry_shader4: enable \n"
"uniform vec2 ViewportSize; \n"
"uniform float StippleFactor; \n"
"out vec2 stippleCoord; \n"
"void main() \n"
"{ \n"
" vec4 pos0 = gl_PositionIn[0]; \n"
" vec4 pos1 = gl_PositionIn[1]; \n"
" // Convert eye coords to window coords \n"
" // Note: we're off by a factor of two here, make up for that below \n"
" vec2 p0 = pos0.xy / pos0.w * ViewportSize; \n"
" vec2 p1 = pos1.xy / pos1.w * ViewportSize; \n"
" float len = length(p0.xy - p1.xy); \n"
" // Emit first vertex \n"
" gl_FrontColor = gl_FrontColorIn[0]; \n"
" gl_Position = pos0; \n"
" stippleCoord.x = 0.0; \n"
" EmitVertex(); \n"
" // Emit second vertex \n"
" gl_FrontColor = gl_FrontColorIn[1]; \n"
" gl_Position = pos1; \n"
" stippleCoord.x = len / StippleFactor / 32.0; // Note: not 16, see above \n"
" EmitVertex(); \n"
"} \n";
if (!ShadersSupported())
exit(1);
if (!glutExtensionSupported("GL_ARB_geometry_shader4")) {
fprintf(stderr, "Sorry, GL_ARB_geometry_shader4 is not supported.\n");
exit(1);
}
VertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
FragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
GeomShader = CompileShaderText(GL_GEOMETRY_SHADER_ARB, geomShaderText);
assert(GeomShader);
Program = LinkShaders3(VertShader, GeomShader, FragShader);
assert(Program);
CheckError(__LINE__);
/*
* The geometry shader accepts lines and produces lines.
*/
glProgramParameteriARB(Program, GL_GEOMETRY_INPUT_TYPE_ARB,
GL_LINES);
glProgramParameteriARB(Program, GL_GEOMETRY_OUTPUT_TYPE_ARB,
GL_LINE_STRIP);
glProgramParameteriARB(Program, GL_GEOMETRY_VERTICES_OUT_ARB, 4);
CheckError(__LINE__);
glLinkProgramARB(Program);
/* check link */
{
GLint stat;
GetProgramiv(Program, GL_LINK_STATUS, &stat);
if (!stat) {
GLchar log[1000];
GLsizei len;
GetProgramInfoLog(Program, 1000, &len, log);
fprintf(stderr, "Shader link error:\n%s\n", log);
}
}
glUseProgram(Program);
uViewportSize = glGetUniformLocation(Program, "ViewportSize");
uStippleFactor = glGetUniformLocation(Program, "StippleFactor");
uStipplePattern = glGetUniformLocation(Program, "StipplePattern");
glUniform1f(uStippleFactor, StippleFactor);
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
assert(glIsProgram(Program));
assert(glIsShader(FragShader));
assert(glIsShader(VertShader));
assert(glIsShader(GeomShader));
glLineStipple(StippleFactor, StipplePattern);
SetStippleUniform(StippleFactor, StipplePattern);
MakePoints();
}
