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Fix the Julia set shader example (#3467)
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* Simplify POI selection

* Improve mouse logic

* Add colour cycles to the shader to show finer details. Works well with high iteration numbers

* Testing things...

* Actually fix zoom. Also allow user to reset camera with 'R'

* Reset max iterations

* Tidying & comments

* Revert to original if statement

* Make mouse logic more readable

* Style conventions

* Coding conventions - f postifx on floating points

* Missed a few f postfixes
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@joshcol9232
joshcol9232 authored Oct 29, 2023
1 parent b486558 commit 975d415
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32 changes: 17 additions & 15 deletions examples/shaders/resources/shaders/glsl100/julia_set.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,30 +6,30 @@ precision mediump float;
varying vec2 fragTexCoord;
varying vec4 fragColor;

uniform vec2 screenDims; // Dimensions of the screen
uniform vec2 c; // c.x = real, c.y = imaginary component. Equation done is z^2 + c
uniform vec2 offset; // Offset of the scale.
uniform float zoom; // Zoom of the scale.

// NOTE: Maximum number of shader for-loop iterations depend on GPU,
// for example, on RasperryPi for this examply only supports up to 60
const int MAX_ITERATIONS = 48; // Max iterations to do
const int maxIterations = 48; // Max iterations to do.
const float colorCycles = 1.0f; // Number of times the color palette repeats.

// Square a complex number
vec2 ComplexSquare(vec2 z)
{
return vec2(
z.x * z.x - z.y * z.y,
z.x * z.y * 2.0
z.x*z.x - z.y*z.y,
z.x*z.y*2.0f
);
}

// Convert Hue Saturation Value (HSV) color into RGB
vec3 Hsv2rgb(vec3 c)
{
vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
vec4 K = vec4(1.0f, 2.0f/3.0f, 1.0f/3.0f, 3.0f);
vec3 p = abs(fract(c.xxx + K.xyz)*6.0f - K.www);
return c.z*mix(K.xxx, clamp(p - K.xxx, 0.0f, 1.0f), c.y);
}

void main()
Expand All @@ -45,8 +45,8 @@ void main()
If the number is below 2, we keep iterating.
But when do we stop iterating if the number is always below 2 (it converges)?
That is what MAX_ITERATIONS is for.
Then we can divide the iterations by the MAX_ITERATIONS value to get a normalized value that we can
That is what maxIterations is for.
Then we can divide the iterations by the maxIterations value to get a normalized value that we can
then map to a color.
We use dot product (z.x * z.x + z.y * z.y) to determine the magnitude (length) squared.
Expand All @@ -55,13 +55,15 @@ void main()

// The pixel coordinates are scaled so they are on the mandelbrot scale
// NOTE: fragTexCoord already comes as normalized screen coordinates but offset must be normalized before scaling and zoom
vec2 z = vec2((fragTexCoord.x + offset.x/screenDims.x)*2.5/zoom, (fragTexCoord.y + offset.y/screenDims.y)*1.5/zoom);
vec2 z = vec2((fragTexCoord.x - 0.5f)*2.5f, (fragTexCoord.y - 0.5f)*1.5f)/zoom;
z.x += offset.x;
z.y += offset.y;

int iter = 0;
for (int iterations = 0; iterations < 60; iterations++)
{
z = ComplexSquare(z) + c; // Iterate function
if (dot(z, z) > 4.0) break;
if (dot(z, z) > 4.0f) break;

iter = iterations;
}
Expand All @@ -72,12 +74,12 @@ void main()
z = ComplexSquare(z) + c;

// This last part smooths the color (again see link above).
float smoothVal = float(iter) + 1.0 - (log(log(length(z)))/log(2.0));
float smoothVal = float(iter) + 1.0f - (log(log(length(z)))/log(2.0f));

// Normalize the value so it is between 0 and 1.
float norm = smoothVal/float(MAX_ITERATIONS);
float norm = smoothVal/float(maxIterations);

// If in set, color black. 0.999 allows for some float accuracy error.
if (norm > 0.999) gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
else gl_FragColor = vec4(Hsv2rgb(vec3(norm, 1.0, 1.0)), 1.0);
if (norm > 0.999f) gl_FragColor = vec4(0.0f, 0.0f, 0.0f, 1.0f);
else gl_FragColor = vec4(Hsv2rgb(vec3(norm*colorCycles, 1.0f, 1.0f)), 1.0f);
}
34 changes: 18 additions & 16 deletions examples/shaders/resources/shaders/glsl330/julia_set.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,28 +7,28 @@ in vec4 fragColor;
// Output fragment color
out vec4 finalColor;

uniform vec2 screenDims; // Dimensions of the screen
uniform vec2 c; // c.x = real, c.y = imaginary component. Equation done is z^2 + c
uniform vec2 offset; // Offset of the scale.
uniform float zoom; // Zoom of the scale.

const int MAX_ITERATIONS = 255; // Max iterations to do.
const int maxIterations = 255; // Max iterations to do.
const float colorCycles = 2.0f; // Number of times the color palette repeats. Can show higher detail for higher iteration numbers.

// Square a complex number
vec2 ComplexSquare(vec2 z)
{
return vec2(
z.x * z.x - z.y * z.y,
z.x * z.y * 2.0
z.x*z.x - z.y*z.y,
z.x*z.y*2.0f
);
}

// Convert Hue Saturation Value (HSV) color into RGB
vec3 Hsv2rgb(vec3 c)
{
vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
vec4 K = vec4(1.0f, 2.0f/3.0f, 1.0f/3.0f, 3.0f);
vec3 p = abs(fract(c.xxx + K.xyz)*6.0f - K.www);
return c.z*mix(K.xxx, clamp(p - K.xxx, 0.0f, 1.0f), c.y);
}

void main()
Expand All @@ -44,8 +44,8 @@ void main()
If the number is below 2, we keep iterating.
But when do we stop iterating if the number is always below 2 (it converges)?
That is what MAX_ITERATIONS is for.
Then we can divide the iterations by the MAX_ITERATIONS value to get a normalized value that we can
That is what maxIterations is for.
Then we can divide the iterations by the maxIterations value to get a normalized value that we can
then map to a color.
We use dot product (z.x * z.x + z.y * z.y) to determine the magnitude (length) squared.
Expand All @@ -54,14 +54,16 @@ void main()

// The pixel coordinates are scaled so they are on the mandelbrot scale
// NOTE: fragTexCoord already comes as normalized screen coordinates but offset must be normalized before scaling and zoom
vec2 z = vec2((fragTexCoord.x + offset.x/screenDims.x)*2.5/zoom, (fragTexCoord.y + offset.y/screenDims.y)*1.5/zoom);
vec2 z = vec2((fragTexCoord.x - 0.5f)*2.5f, (fragTexCoord.y - 0.5f)*1.5f)/zoom;
z.x += offset.x;
z.y += offset.y;

int iterations = 0;
for (iterations = 0; iterations < MAX_ITERATIONS; iterations++)
for (iterations = 0; iterations < maxIterations; iterations++)
{
z = ComplexSquare(z) + c; // Iterate function

if (dot(z, z) > 4.0) break;
if (dot(z, z) > 4.0f) break;
}

// Another few iterations decreases errors in the smoothing calculation.
Expand All @@ -70,12 +72,12 @@ void main()
z = ComplexSquare(z) + c;

// This last part smooths the color (again see link above).
float smoothVal = float(iterations) + 1.0 - (log(log(length(z)))/log(2.0));
float smoothVal = float(iterations) + 1.0f - (log(log(length(z)))/log(2.0f));

// Normalize the value so it is between 0 and 1.
float norm = smoothVal/float(MAX_ITERATIONS);
float norm = smoothVal/float(maxIterations);

// If in set, color black. 0.999 allows for some float accuracy error.
if (norm > 0.999) finalColor = vec4(0.0, 0.0, 0.0, 1.0);
else finalColor = vec4(Hsv2rgb(vec3(norm, 1.0, 1.0)), 1.0);
if (norm > 0.999f) finalColor = vec4(0.0f, 0.0f, 0.0f, 1.0f);
else finalColor = vec4(Hsv2rgb(vec3(norm*colorCycles, 1.0f, 1.0f)), 1.0f);
}
96 changes: 51 additions & 45 deletions examples/shaders/shaders_julia_set.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,12 +9,12 @@
*
* Example originally created with raylib 2.5, last time updated with raylib 4.0
*
* Example contributed by eggmund (@eggmund) and reviewed by Ramon Santamaria (@raysan5)
* Example contributed by Josh Colclough (@joshcol9232) and reviewed by Ramon Santamaria (@raysan5)
*
* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
* BSD-like license that allows static linking with closed source software
*
* Copyright (c) 2019-2023 eggmund (@eggmund) and Ramon Santamaria (@raysan5)
* Copyright (c) 2019-2023 Josh Colclough (@joshcol9232) and Ramon Santamaria (@raysan5)
*
********************************************************************************************/

Expand All @@ -37,17 +37,20 @@ const float pointsOfInterest[6][2] =
{ -0.70176f, -0.3842f },
};

const int screenWidth = 800;
const int screenHeight = 450;
const float zoomSpeed = 1.01f;
const float offsetSpeedMul = 2.0f;

const float startingZoom = 0.75f;

//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;

//SetConfigFlags(FLAG_WINDOW_HIGHDPI);
InitWindow(screenWidth, screenHeight, "raylib [shaders] example - julia sets");

// Load julia set shader
Expand All @@ -61,28 +64,22 @@ int main(void)
float c[2] = { pointsOfInterest[0][0], pointsOfInterest[0][1] };

// Offset and zoom to draw the julia set at. (centered on screen and default size)
float offset[2] = { -(float)GetScreenWidth()/2, -(float)GetScreenHeight()/2 };
float zoom = 1.0f;

Vector2 offsetSpeed = { 0.0f, 0.0f };
float offset[2] = { 0.0f, 0.0f };
float zoom = startingZoom;

// Get variable (uniform) locations on the shader to connect with the program
// NOTE: If uniform variable could not be found in the shader, function returns -1
int cLoc = GetShaderLocation(shader, "c");
int zoomLoc = GetShaderLocation(shader, "zoom");
int offsetLoc = GetShaderLocation(shader, "offset");

// Tell the shader what the screen dimensions, zoom, offset and c are
float screenDims[2] = { (float)GetScreenWidth(), (float)GetScreenHeight() };
SetShaderValue(shader, GetShaderLocation(shader, "screenDims"), screenDims, SHADER_UNIFORM_VEC2);

// Upload the shader uniform values!
SetShaderValue(shader, cLoc, c, SHADER_UNIFORM_VEC2);
SetShaderValue(shader, zoomLoc, &zoom, SHADER_UNIFORM_FLOAT);
SetShaderValue(shader, offsetLoc, offset, SHADER_UNIFORM_VEC2);

int incrementSpeed = 0; // Multiplier of speed to change c value
bool showControls = true; // Show controls
bool pause = false; // Pause animation

SetTargetFPS(60); // Set our game to run at 60 frames-per-second
//--------------------------------------------------------------------------------------
Expand Down Expand Up @@ -110,42 +107,50 @@ int main(void)
SetShaderValue(shader, cLoc, c, SHADER_UNIFORM_VEC2);
}

if (IsKeyPressed(KEY_SPACE)) pause = !pause; // Pause animation (c change)
if (IsKeyPressed(KEY_F1)) showControls = !showControls; // Toggle whether or not to show controls

if (!pause)
// If "R" is pressed, reset zoom and offset.
if (IsKeyPressed(KEY_R))
{
if (IsKeyPressed(KEY_RIGHT)) incrementSpeed++;
else if (IsKeyPressed(KEY_LEFT)) incrementSpeed--;

// TODO: The idea is to zoom and move around with mouse
// Probably offset movement should be proportional to zoom level
if (IsMouseButtonDown(MOUSE_BUTTON_LEFT) || IsMouseButtonDown(MOUSE_BUTTON_RIGHT))
{
if (IsMouseButtonDown(MOUSE_BUTTON_LEFT)) zoom += zoom*0.003f;
if (IsMouseButtonDown(MOUSE_BUTTON_RIGHT)) zoom -= zoom*0.003f;

Vector2 mousePos = GetMousePosition();
zoom = startingZoom;
offset[0] = 0.0f;
offset[1] = 0.0f;
SetShaderValue(shader, zoomLoc, &zoom, SHADER_UNIFORM_FLOAT);
SetShaderValue(shader, offsetLoc, offset, SHADER_UNIFORM_VEC2);
}

offsetSpeed.x = mousePos.x -(float)screenWidth/2;
offsetSpeed.y = mousePos.y -(float)screenHeight/2;
if (IsKeyPressed(KEY_SPACE)) incrementSpeed = 0; // Pause animation (c change)
if (IsKeyPressed(KEY_F1)) showControls = !showControls; // Toggle whether or not to show controls

// Slowly move camera to targetOffset
offset[0] += GetFrameTime()*offsetSpeed.x*0.8f;
offset[1] += GetFrameTime()*offsetSpeed.y*0.8f;
}
else offsetSpeed = (Vector2){ 0.0f, 0.0f };
if (IsKeyPressed(KEY_RIGHT)) incrementSpeed++;
else if (IsKeyPressed(KEY_LEFT)) incrementSpeed--;

// If either left or right button is pressed, zoom in/out.
if (IsMouseButtonDown(MOUSE_BUTTON_LEFT) || IsMouseButtonDown(MOUSE_BUTTON_RIGHT))
{
// Change zoom. If Mouse left -> zoom in. Mouse right -> zoom out.
zoom *= IsMouseButtonDown(MOUSE_BUTTON_LEFT)? zoomSpeed : 1.0f/zoomSpeed;

const Vector2 mousePos = GetMousePosition();
Vector2 offsetVelocity;
// Find the velocity at which to change the camera. Take the distance of the mouse
// from the center of the screen as the direction, and adjust magnitude based on
// the current zoom.
offsetVelocity.x = (mousePos.x/(float)screenWidth - 0.5f)*offsetSpeedMul/zoom;
offsetVelocity.y = (mousePos.y/(float)screenHeight - 0.5f)*offsetSpeedMul/zoom;

// Apply move velocity to camera
offset[0] += GetFrameTime()*offsetVelocity.x;
offset[1] += GetFrameTime()*offsetVelocity.y;

// Update the shader uniform values!
SetShaderValue(shader, zoomLoc, &zoom, SHADER_UNIFORM_FLOAT);
SetShaderValue(shader, offsetLoc, offset, SHADER_UNIFORM_VEC2);

// Increment c value with time
float amount = GetFrameTime()*incrementSpeed*0.0005f;
c[0] += amount;
c[1] += amount;

SetShaderValue(shader, cLoc, c, SHADER_UNIFORM_VEC2);
}

// Increment c value with time
const float dc = GetFrameTime()*(float)incrementSpeed*0.0005f;
c[0] += dc;
c[1] += dc;
SetShaderValue(shader, cLoc, c, SHADER_UNIFORM_VEC2);
//----------------------------------------------------------------------------------

// Draw
Expand Down Expand Up @@ -178,7 +183,8 @@ int main(void)
DrawText("Press KEY_F1 to toggle these controls", 10, 30, 10, RAYWHITE);
DrawText("Press KEYS [1 - 6] to change point of interest", 10, 45, 10, RAYWHITE);
DrawText("Press KEY_LEFT | KEY_RIGHT to change speed", 10, 60, 10, RAYWHITE);
DrawText("Press KEY_SPACE to pause movement animation", 10, 75, 10, RAYWHITE);
DrawText("Press KEY_SPACE to stop movement animation", 10, 75, 10, RAYWHITE);
DrawText("Press KEY_R to recenter the camera", 10, 90, 10, RAYWHITE);
}
EndDrawing();
//----------------------------------------------------------------------------------
Expand Down

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