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Rewrite spheric mirror to make it more efficient
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The old version rewrote VBO about 150×3 times per frame, which is very
inefficient, especially given that the data written never change.
This version writes these constant data once in the constructor of the
distorter and uses them on rendering.

Fixes #3535
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@10110111
10110111 committed Oct 17, 2024
1 parent 9f76b14 commit 9e4409b
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Showing 2 changed files with 181 additions and 16 deletions.
173 changes: 157 additions & 16 deletions src/core/StelViewportEffect.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,19 @@
#include <QFile>
#include <QDir>

namespace
{
constexpr int SPHERIC_MIRROR_COORDS_PER_VERTEX = 2;
constexpr int SPHERIC_MIRROR_COORDS_PER_COLOR = 4;
constexpr int SPHERIC_MIRROR_COORDS_PER_TEXCOORD = 2;
enum
{
VERTEX_ATTRIB_INDEX,
COLOR_ATTRIB_INDEX,
TEXCOORD_ATTRIB_INDEX,
};
}

void StelViewportEffect::paintViewportBuffer(const QOpenGLFramebufferObject* buf) const
{
StelPainter sPainter(StelApp::getInstance().getCore()->getProjection2d());
Expand All @@ -51,6 +64,8 @@ StelViewportDistorterFisheyeToSphericMirror::StelViewportDistorterFisheyeToSpher
, screen_h(screen_h)
, originalProjectorParams(StelApp::getInstance().getCore()->getCurrentStelProjectorParams())
, texture_point_array(Q_NULLPTR)
, vao(new QOpenGLVertexArrayObject)
, verticesVBO(new QOpenGLBuffer(QOpenGLBuffer::VertexBuffer))
{
QSettings& conf = *StelApp::getInstance().getSettings();
StelCore* core = StelApp::getInstance().getCore();
Expand Down Expand Up @@ -236,12 +251,132 @@ StelViewportDistorterFisheyeToSphericMirror::StelViewportDistorterFisheyeToSpher
}
}
delete[] vertex_point_array;

StelApp::getInstance().ensureGLContextCurrent();
setupBuffers();
setupShaders();
}

void StelViewportDistorterFisheyeToSphericMirror::setupShaders()
{
QOpenGLShader vsh(QOpenGLShader::Vertex);
const auto vsrc =
StelOpenGL::globalShaderPrefix(StelOpenGL::VERTEX_SHADER) +
"ATTRIBUTE highp vec3 vertex;\n"
"ATTRIBUTE mediump vec2 texCoord;\n"
"ATTRIBUTE mediump vec4 color;\n"
"uniform mediump mat4 projectionMatrix;\n"
"VARYING mediump vec2 texc;\n"
"VARYING mediump vec4 outColor;\n"
"void main()\n"
"{\n"
" gl_Position = projectionMatrix * vec4(vertex, 1.);\n"
" texc = texCoord;\n"
" outColor = color;\n"
"}\n";
vsh.compileSourceCode(vsrc);
if (!vsh.log().isEmpty())
qWarning().noquote() << "StelViewportDistorterFisheyeToSphericMirror: Warnings while compiling vertex shader: " << vsh.log();

QOpenGLShader fsh(QOpenGLShader::Fragment);
const auto fsrc =
StelOpenGL::globalShaderPrefix(StelOpenGL::FRAGMENT_SHADER) +
"VARYING mediump vec2 texc;\n"
"VARYING mediump vec4 outColor;\n"
"uniform sampler2D tex;\n"
"void main()\n"
"{\n"
" FRAG_COLOR = texture2D(tex, texc)*outColor;\n"
"}\n";
fsh.compileSourceCode(fsrc);
if (!fsh.log().isEmpty())
qWarning().noquote() << "StelViewportDistorterFisheyeToSphericMirror: Warnings while compiling fragment shader: " << fsh.log();

shaderProgram.reset(new QOpenGLShaderProgram(QOpenGLContext::currentContext()));
shaderProgram->addShader(&vsh);
shaderProgram->addShader(&fsh);
shaderProgram->bindAttributeLocation("vertex", VERTEX_ATTRIB_INDEX);
shaderProgram->bindAttributeLocation("color", COLOR_ATTRIB_INDEX);
shaderProgram->bindAttributeLocation("texCoord", TEXCOORD_ATTRIB_INDEX);
StelPainter::linkProg(shaderProgram.get(), "spheric mirror distortion shader program");
shaderVars.projectionMatrix = shaderProgram->uniformLocation("projectionMatrix");
shaderVars.texture = shaderProgram->uniformLocation("tex");
}

void StelViewportDistorterFisheyeToSphericMirror::setupBuffers()
{
verticesVBO->create();
verticesVBO->setUsagePattern(QOpenGLBuffer::StaticDraw);
verticesVBO->bind();
const int colorElemSize = SPHERIC_MIRROR_COORDS_PER_COLOR * sizeof(GLfloat);
const int vertElemSize = SPHERIC_MIRROR_COORDS_PER_VERTEX * sizeof(GLfloat);
const int texCoordElemSize = SPHERIC_MIRROR_COORDS_PER_TEXCOORD * sizeof(GLfloat);
const int numberOfVerticesToCopy = displayVertexList.size();
const auto bufferSize = vertElemSize*numberOfVerticesToCopy +
texCoordElemSize*numberOfVerticesToCopy +
colorElemSize*numberOfVerticesToCopy;
verticesVBO->allocate(bufferSize);
vboVertexDataOffset = 0;
const auto vertexDataSize = vertElemSize*numberOfVerticesToCopy;
verticesVBO->write(vboVertexDataOffset, displayVertexList.constData(), vertexDataSize);
vboTexCoordDataOffset = vertexDataSize;
const auto texCoordDataSize = texCoordElemSize*numberOfVerticesToCopy;
verticesVBO->write(vboTexCoordDataOffset, displayTexCoordList.constData(), texCoordDataSize);
vboColorDataOffset = vertexDataSize + texCoordDataSize;
const auto colorDataSize = colorElemSize*numberOfVerticesToCopy;
verticesVBO->write(vboColorDataOffset, displayColorList.constData(), colorDataSize);
verticesVBO->release();

vao->create();
bindVAO();
setupCurrentVAO();
releaseVAO();
}

void StelViewportDistorterFisheyeToSphericMirror::setupCurrentVAO() const
{
auto& gl = *QOpenGLContext::currentContext()->functions();
verticesVBO->bind();
gl.glVertexAttribPointer(VERTEX_ATTRIB_INDEX, SPHERIC_MIRROR_COORDS_PER_VERTEX, GL_FLOAT,
false, 0, reinterpret_cast<const void*>(vboVertexDataOffset));
gl.glVertexAttribPointer(COLOR_ATTRIB_INDEX, SPHERIC_MIRROR_COORDS_PER_COLOR, GL_FLOAT,
false, 0, reinterpret_cast<const void*>(vboColorDataOffset));
gl.glVertexAttribPointer(TEXCOORD_ATTRIB_INDEX, SPHERIC_MIRROR_COORDS_PER_TEXCOORD, GL_FLOAT,
false, 0, reinterpret_cast<const void*>(vboTexCoordDataOffset));
verticesVBO->release();
gl.glEnableVertexAttribArray(VERTEX_ATTRIB_INDEX);
gl.glEnableVertexAttribArray(COLOR_ATTRIB_INDEX);
gl.glEnableVertexAttribArray(TEXCOORD_ATTRIB_INDEX);
}

void StelViewportDistorterFisheyeToSphericMirror::bindVAO() const
{
if(vao->isCreated())
vao->bind();
else
setupCurrentVAO();
}

void StelViewportDistorterFisheyeToSphericMirror::releaseVAO() const
{
if(vao->isCreated())
{
vao->release();
}
else
{
auto& gl = *QOpenGLContext::currentContext()->functions();
gl.glDisableVertexAttribArray(VERTEX_ATTRIB_INDEX);
gl.glDisableVertexAttribArray(COLOR_ATTRIB_INDEX);
gl.glDisableVertexAttribArray(TEXCOORD_ATTRIB_INDEX);
}
}


StelViewportDistorterFisheyeToSphericMirror::~StelViewportDistorterFisheyeToSphericMirror(void)
{
StelApp::getInstance().ensureGLContextCurrent(); // Make sure that VBO & VAO will be properly deleted

if (texture_point_array)
delete[] texture_point_array;
StelApp::getInstance().getCore()->setCurrentStelProjectorParams(originalProjectorParams);
Expand Down Expand Up @@ -323,24 +458,30 @@ void StelViewportDistorterFisheyeToSphericMirror::distortXY(qreal &x, qreal &y)

void StelViewportDistorterFisheyeToSphericMirror::paintViewportBuffer(const QOpenGLFramebufferObject* buf) const
{
StelPainter sPainter(StelApp::getInstance().getCore()->getProjection2d());
QOpenGLFunctions* gl = sPainter.glFuncs();
GL(gl->glActiveTexture(GL_TEXTURE0));
GL(gl->glBindTexture(GL_TEXTURE_2D, buf->texture()));
GL(gl->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR));
GL(gl->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR));
sPainter.setBlending(false);

sPainter.enableClientStates(true, true, true);
sPainter.setColorPointer(4, GL_FLOAT, displayColorList.constData());
sPainter.setVertexPointer(2, GL_FLOAT, displayVertexList.constData());
sPainter.setTexCoordPointer(2, GL_FLOAT, displayTexCoordList.constData());
const auto prj = StelApp::getInstance().getCore()->getProjection2d();
auto& gl = *QOpenGLContext::currentContext()->functions();
const int texUnit = 0;
GL(gl.glActiveTexture(GL_TEXTURE0 + texUnit));
GL(gl.glBindTexture(GL_TEXTURE_2D, buf->texture()));
GL(gl.glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR));
GL(gl.glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR));

shaderProgram->bind();
const Mat4f& m = prj->getProjectionMatrix();
const QMatrix4x4 qMat(m[0], m[4], m[8], m[12], m[1], m[5], m[9], m[13], m[2], m[6], m[10], m[14], m[3], m[7], m[11], m[15]);
shaderProgram->setUniformValue(shaderVars.projectionMatrix, qMat);
shaderProgram->setUniformValue(shaderVars.texture, texUnit);

bindVAO();
for (int j=0;j<max_y;j++)
{
sPainter.drawFromArray(StelPainter::TriangleStrip, (max_x+1)*2, j*(max_x+1)*2, false);
GL(gl.glDrawArrays(GL_TRIANGLE_STRIP, j*(max_x+1)*2, (max_x+1)*2));
}
sPainter.enableClientStates(false);
GL(gl->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
GL(gl->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
releaseVAO();

shaderProgram->release();

GL(gl.glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
GL(gl.glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
}

24 changes: 24 additions & 0 deletions src/core/StelViewportEffect.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,12 @@
#ifndef STELVIEWPORTEFFECT_HPP
#define STELVIEWPORTEFFECT_HPP

#include <memory>
#include "VecMath.hpp"
#include "StelProjector.hpp"
#include <QOpenGLBuffer>
#include <QOpenGLShaderProgram>
#include <QOpenGLVertexArrayObject>

class QOpenGLFramebufferObject;

Expand Down Expand Up @@ -54,6 +58,14 @@ class StelViewportDistorterFisheyeToSphericMirror : public StelViewportEffect
QString getName() const override {return "sphericMirrorDistorter";}
void paintViewportBuffer(const QOpenGLFramebufferObject* buf) const override;
void distortXY(qreal& x, qreal& y) const override;

private:
void setupShaders();
void setupBuffers();
void bindVAO() const;
void releaseVAO() const;
void setupCurrentVAO() const;

private:
const int screen_w;
const int screen_h;
Expand All @@ -68,6 +80,18 @@ class StelViewportDistorterFisheyeToSphericMirror : public StelViewportEffect
QVector<Vec2f> displayVertexList;
QVector<Vec4f> displayColorList;
QVector<Vec2f> displayTexCoordList;
std::unique_ptr<QOpenGLVertexArrayObject> vao;
std::unique_ptr<QOpenGLBuffer> verticesVBO;
std::unique_ptr<QOpenGLShaderProgram> shaderProgram;
int vboVertexDataOffset;
int vboTexCoordDataOffset;
int vboColorDataOffset;
struct ShaderVars
{
int projectionMatrix;
int texture;
};
ShaderVars shaderVars;
};

#endif // STELVIEWPORTEFFECT_HPP
Expand Down

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