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/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2018 Serge Bazanski <q3k@symbioticeda.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#ifndef LINESHADER_H
#define LINESHADER_H
#include <QOpenGLBuffer>
#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLWidget>
#include "nextpnr.h"
NEXTPNR_NAMESPACE_BEGIN
// Vertex2DPOD is a structure of X, Y coordinates that can be passed to OpenGL
// directly.
NPNR_PACKED_STRUCT(struct Vertex2DPOD {
GLfloat x;
GLfloat y;
Vertex2DPOD(GLfloat X, GLfloat Y) : x(X), y(Y) {}
});
// LineShaderData is a built set of vertices that can be rendered by the
// LineShader.
// Each LineShaderData can have its' own color and thickness.
struct LineShaderData
{
std::vector<Vertex2DPOD> vertices;
std::vector<Vertex2DPOD> normals;
std::vector<GLfloat> miters;
std::vector<GLuint> indices;
LineShaderData(void) {}
void clear(void)
{
vertices.clear();
normals.clear();
miters.clear();
indices.clear();
}
};
// PolyLine is a set of segments defined by points, that can be built to a
// ShaderLine for GPU rendering.
class PolyLine
{
private:
std::vector<QVector2D> points_;
bool closed_;
void buildPoint(LineShaderData *building, const QVector2D *prev, const QVector2D *cur, const QVector2D *next) const;
public:
// Create an empty PolyLine.
PolyLine(bool closed = false) : closed_(closed) {}
// Create a non-closed polyline consisting of one segment.
PolyLine(float x0, float y0, float x1, float y1) : closed_(false)
{
point(x0, y0);
point(x1, y1);
}
// Add a point to the PolyLine.
void point(float x, float y) { points_.push_back(QVector2D(x, y)); }
// Built PolyLine to shader data.
void build(LineShaderData &target) const;
// Set whether line is closed (ie. a loop).
void setClosed(bool closed) { closed_ = closed; }
};
// LineShader is an OpenGL shader program that renders LineShaderData on the
// GPU.
// The LineShader expects two vertices per line point. It will push those
// vertices along the given normal * miter. This is used to 'stretch' the line
// to be as wide as the given thickness. The normal and miter are calculated
// by the PolyLine build method in order to construct a constant thickness line
// with miter edge joints.
//
// +------+------+
//
// |
// PolyLine.build()
// |
// V
//
// ^ ^ ^
// | | | <--- normal vectors (x2, pointing in the same
// +/+----+/+----+/+ direction)
//
// |
// vertex shader
// |
// V
//
// +------+------+ ^ by normal * miter * thickness/2
// | | |
// +------+------+ V by normal * miter * thickness/2
//
// (miter is flipped for every second vertex generated)
class LineShader
{
private:
QObject *parent_;
QOpenGLShaderProgram *program_;
// GL attribute locations.
struct
{
// original position of line vertex
GLuint position;
// normal by which vertex should be translated
GLuint normal;
// scalar defining:
// - how stretched the normal vector should be to
// compensate for bends
// - which way the normal should be applied (+1 for one vertex, -1
// for the other)
GLuint miter;
} attributes_;
// GL buffers
struct
{
QOpenGLBuffer position;
QOpenGLBuffer normal;
QOpenGLBuffer miter;
QOpenGLBuffer index;
} buffers_;
// GL uniform locations.
struct
{
// combines m/v/p matrix to apply
GLuint projection;
// desired thickness of line
GLuint thickness;
// color of line
GLuint color;
} uniforms_;
QOpenGLVertexArrayObject vao_;
public:
LineShader(QObject *parent) : parent_(parent), program_(nullptr)
{
buffers_.position = QOpenGLBuffer(QOpenGLBuffer::VertexBuffer);
buffers_.position.setUsagePattern(QOpenGLBuffer::StaticDraw);
buffers_.normal = QOpenGLBuffer(QOpenGLBuffer::VertexBuffer);
buffers_.normal.setUsagePattern(QOpenGLBuffer::StaticDraw);
buffers_.miter = QOpenGLBuffer(QOpenGLBuffer::VertexBuffer);
buffers_.miter.setUsagePattern(QOpenGLBuffer::StaticDraw);
buffers_.index = QOpenGLBuffer(QOpenGLBuffer::IndexBuffer);
buffers_.index.setUsagePattern(QOpenGLBuffer::StaticDraw);
}
static constexpr const char *vertexShaderSource_ =
"#version 110\n"
"attribute highp vec2 position;\n"
"attribute highp vec2 normal;\n"
"attribute highp float miter;\n"
"uniform highp float thickness;\n"
"uniform highp mat4 projection;\n"
"void main() {\n"
" vec2 p = position.xy + vec2(normal * thickness/2.0 / miter);\n"
" gl_Position = projection * vec4(p, 0.0, 1.0);\n"
"}\n";
static constexpr const char *fragmentShaderSource_ = "#version 110\n"
"uniform lowp vec4 color;\n"
"void main() {\n"
" gl_FragColor = color;\n"
"}\n";
// Must be called on initialization.
bool compile(void);
// Render a LineShaderData with a given M/V/P transformation.
void draw(const LineShaderData &data, const QColor &color, float thickness, const QMatrix4x4 &projection);
};
NEXTPNR_NAMESPACE_END
#endif
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