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Add simple tile visibility checking in the ViewModule #5

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Sep 15, 2014
Merged

Add simple tile visibility checking in the ViewModule #5

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edbf4e9
Add simple tile visibility checking in the ViewModule
matteblair Sep 12, 2014
113e4ec
Add trailing newline. Because reasons.
matteblair Sep 12, 2014
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4 changes: 2 additions & 2 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -34,9 +34,9 @@ ios:
xcodebuild -workspace ios/TangramiOS.xcworkspace -scheme TangramiOS -destination 'platform=iOS Simulator,name=iPhone Retina (3.5-inch)'

osx/lib/libtangram.so: core/tangram.cpp core/tangram.h
cc -o osx/lib/libtangram.so core/tangram.cpp osx/src/platform_osx.cpp -Icore -DPLATFORM_OSX -lglfw3 -framework OpenGL -shared
clang++ -o osx/lib/libtangram.so core/tangram.cpp core/viewModule/viewModule.cpp osx/src/platform_osx.cpp -Icore -Icore/include -DPLATFORM_OSX -lglfw3 -framework OpenGL -shared -std=c++11

osx/bin/TangramOSX: osx/lib/libtangram.so
clang -o osx/bin/TangramOSX osx/src/main.cpp osx/lib/libtangram.so -DPLATFORM_OSX -lglfw3 -framework Cocoa -framework IOKit -framework OpenGL -framework CoreVideo
clang++ -o osx/bin/TangramOSX osx/src/main.cpp osx/lib/libtangram.so -Icore/include -DPLATFORM_OSX -lglfw3 -framework Cocoa -framework IOKit -framework OpenGL -framework CoreVideo

osx: osx/bin/TangramOSX
74 changes: 60 additions & 14 deletions core/viewModule/viewModule.cpp
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Original file line number Diff line number Diff line change
@@ -1,17 +1,19 @@
#include "viewModule.h"

ViewModule::ViewModule(float width, float height) {
init(width, height);
ViewModule::ViewModule(float _width, float _height) {
init(_width, _height);
}

ViewModule::ViewModule() {
init(800, 600);
}

void ViewModule::init(float width, float height) {
void ViewModule::init(float _width, float _height) {

m_dirty = true;

// Set up projection matrix based on input width and height with an arbitrary zoom
setAspect(width, height);
setAspect(_width, _height);
setZoom(16); // Arbitrary zoom for testing

// Set up view matrix
Expand All @@ -22,30 +24,30 @@ void ViewModule::init(float width, float height) {

}

void ViewModule::setAspect(float width, float height) {
void ViewModule::setAspect(float _width, float _height) {

m_aspect = width / height;
m_aspect = _width / _height;
setZoom(m_zoom);

}

void ViewModule::setPosition(float x, float y) {
void ViewModule::setPosition(float _x, float _y) {

translate(x - m_pos.x, y - m_pos.y);
translate(_x - m_pos.x, _y - m_pos.y);

}

void ViewModule::translate(float dx, float dy) {
void ViewModule::translate(float _dx, float _dy) {

glm::translate(m_view, glm::vec3(dx, dy, 0.0));
m_pos.x += dx;
m_pos.y += dy;
glm::translate(m_view, glm::vec3(_dx, _dy, 0.0));
m_pos.x += _dx;
m_pos.y += _dy;

}

void ViewModule::setZoom(int z) {
void ViewModule::setZoom(int _z) {

m_zoom = z;
m_zoom = _z;
float tileSize = 2 * PI * EARTH_RADIUS_M / pow(2, m_zoom);
m_height = 3 * tileSize; // Set viewport size to ~3 tiles vertically
m_width = m_height * m_aspect; // Size viewport width to match aspect ratio
Expand All @@ -60,3 +62,47 @@ glm::mat2 ViewModule::getBoundsRect() {
return glm::mat2(m_pos.x - hw, m_pos.y - hh, m_pos.x + hw, m_pos.y + hh);

}

const std::vector<glm::ivec3>& ViewModule::getVisibleTiles() {

if (!m_dirty) {
return m_visibleTiles;
}

m_visibleTiles.clear();

float tileSize = 2 * PI * EARTH_RADIUS_M / pow(2, m_zoom);
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A small thing.
Its always recommended to do multiplication over division. Sometime the performance gains are huge..
Some Floating point processing multiplication can be 5 to 8 times faster than floating point division.

float inversePowZoon = 1/pow(2, m_zoom);
float tileSize = 2_PI_EARTH_RADIUS_M*inversePowZoon;

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@tallytalwar really?? Do you have some docs to point to on that - curious to read more.

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yup... hence use of bitwise operators is also recommended. (multiplication by 2 should be replaced with one right shift, and division by 2 should be replaced by one left shift)..

there are many more such optimizations ...
http://books.google.com/books?id=IRN0IEXJzKEC&pg=PA92&lpg=PA92&dq=floating+point+division+multiplication+optimization+c%2B%2B&source=bl&ots=P1mjHg8EAs&sig=sZD71hukKFcJ6RaBJz4Q5awC9gs&hl=en&sa=X&ei=hZUXVNvRENSn8QGvq4HoBw&ved=0CFEQ6AEwBw#v=onepage&q=floating%20point%20division%20multiplication%20optimization%20c%2B%2B&f=false

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Also this: http://msdn.microsoft.com/en-us/library/aa289157(v=vs.71).aspx

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Yep but those references are over a decade old, so I wonder if they still
apply. Bit-shifting is an old x86 technique, I use it out of habit. I
wonder though if the compiler won't apply these optimizations automatically
anyway... worth reading up on just to know.

On Mon, Sep 15, 2014 at 9:45 PM, Varun notifications@github.com wrote:

In core/viewModule/viewModule.cpp:

@@ -60,3 +62,47 @@ glm::mat2 ViewModule::getBoundsRect() {
return glm::mat2(m_pos.x - hw, m_pos.y - hh, m_pos.x + hw, m_pos.y + hh);

}
+
+const std::vectorglm::ivec3& ViewModule::getVisibleTiles() {
+

  • if (!m_dirty) {
  •   return m_visibleTiles;
  • }
  • m_visibleTiles.clear();
  • float tileSize = 2 * PI * EARTH_RADIUS_M / pow(2, m_zoom);

yup... hence use of bitwise operators is also recommended. (multiplication
by 2 should be replaced with one right shift, and division by 2 should be
replaced by one left shift)..

there are many more such optimizations ...

http://books.google.com/books?id=IRN0IEXJzKEC&pg=PA92&lpg=PA92&dq=floating+point+division+multiplication+optimization+c%2B%2B&source=bl&ots=P1mjHg8EAs&sig=sZD71hukKFcJ6RaBJz4Q5awC9gs&hl=en&sa=X&ei=hZUXVNvRENSn8QGvq4HoBw&ved=0CFEQ6AEwBw#v=onepage&q=floating%20point%20division%20multiplication%20optimization%20c%2B%2B&f=false

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https://github.com/tangram-map/tangram-es/pull/5/files#r17579753.

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Sure will do..

What I have been told by developers I have interacted with at DWA and other gaming studios that these still apply. But I will still confirm. If compiler optimization are there then it will save us a lot of pain. :D


float vpLeftEdge = m_pos.x - m_width/2;
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Same .. instead of dividing by 2, multiply by 0.5.

float vpRightEdge = vpLeftEdge + m_width;
float vpBottomEdge = m_pos.y - m_height/2;
float vpTopEdge = vpBottomEdge + m_height;

int tileX = (int) vpLeftEdge / tileSize;
int tileY = (int) vpBottomEdge / tileSize;

float x = tileX * tileSize;
float y = tileY * tileSize;

while (x < vpRightEdge) {

while (y < vpTopEdge) {

m_visibleTiles.push_back(glm::ivec3(tileX, tileY, m_zoom));
tileY++;
y += tileSize;

}

tileY = (int) vpBottomEdge / tileSize;
y = tileY * tileSize;

tileX++;
x += tileSize;
}

m_dirty = false;

return m_visibleTiles;

}
19 changes: 11 additions & 8 deletions core/viewModule/viewModule.h
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Expand Up @@ -23,24 +23,27 @@ class ViewModule {

public:

ViewModule(float width, float height);
ViewModule(float _width, float _height);
ViewModule();

void setAspect(float width, float height);
void setPosition(float x, float y);
void setZoom(int z);
void translate(float dx, float dy);
void zoom(int dz);
void setAspect(float _width, float _height);
void setPosition(float _x, float _y);
void setZoom(int _z);
void translate(float _dx, float _dy);
void zoom(int _dz);

int getZoom() { return m_zoom; };
glm::vec3 getPosition() { return m_pos; };
glm::mat4 getViewMatrix() { return m_view; };
glm::mat4 getProjectionMatrix() { return m_proj; };

glm::mat2 getBoundsRect(); // Returns a rectangle of the current view range as [[x_min, y_min][x_max, y_max]]
const std::vector<glm::ivec3>& getVisibleTiles();

private:

bool m_dirty;
std::vector<glm::ivec3> m_visibleTiles;
glm::vec3 m_pos;
glm::mat4 m_view;
glm::mat4 m_proj;
Expand All @@ -49,6 +52,6 @@ class ViewModule {
float m_height;
float m_aspect;

void init(float width, float height);
void init(float _width, float _height);

};
};