Added julia set shader example.

examples/Makefile

@@ -423,6 +423,7 @@ EXAMPLES = \
     shaders/shaders_postprocessing \
     shaders/shaders_raymarching \
     shaders/shaders_palette_switch \
+    shaders/shaders_julia_set \
     audio/audio_sound_loading \
     audio/audio_music_stream \
     audio/audio_module_playing \

examples/shaders/resources/shaders/glsl330/julia_shader.fs

@@ -0,0 +1,86 @@
+#version 330
+
+// Input vertex attributes (from vertex shader)
+
+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.
+
+// Output fragment color
+out vec4 finalColor;
+
+const int MAX_ITERATIONS = 255; // Max iterations to do.
+
+// Square a complex number
+vec2 complexSquare(vec2 z)
+{
+   return vec2(
+      z.x * z.x - z.y * z.y,
+      z.x * z.y * 2.0
+   );
+}
+
+// Convert Hue Saturation Value 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);
+}
+
+
+void main()
+{
+    // The pixel coordinates scaled so they are on the mandelbrot scale. 
+    vec2 z = vec2(((gl_FragCoord.x + offset.x)/screenDims.x) * 2.5 * zoom,
+                  ((screenDims.y - gl_FragCoord.y + offset.y)/screenDims.y) * 1.5 * zoom); // y also flipped due to opengl
+    int iterations = 0;
+
+    /*
+      Julia sets use a function z^2 + c, where c is a constant.
+      This function is iterated until the nature of the point is determined.
+
+      If the magnitude of the number becomes greater than 2, then from that point onward
+      the number will get bigger and bigger, and will never get smaller (tends towards infinity).
+      2^2 = 4, 4^2 = 8 and so on.
+      So at 2 we stop iterating.
+
+      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
+      then map to a color.
+
+      We use dot product (z.x * z.x + z.y * z.y) to determine the magnitude (length) squared.
+      And once the magnitude squared is > 4, then magnitude > 2 is also true (saves computational power).
+    */
+    for (iterations = 0; iterations < MAX_ITERATIONS; iterations++)
+    {
+        z = complexSquare(z) + c;  // Iterate function
+        if (dot(z, z) > 4.0)
+        {
+            break;
+        }
+    }
+    
+    // Another few iterations decreases errors in the smoothing calculation.
+    // See http://linas.org/art-gallery/escape/escape.html for more information.
+    z = complexSquare(z) + c;
+    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));
+    
+    // Normalize the value so it is between 0 and 1.
+    float norm = smoothVal/float(MAX_ITERATIONS);
+
+    // 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);
+    }
+}

examples/shaders/shaders_julia_set.c

@@ -0,0 +1,213 @@
+/*******************************************************************************************
+*
+*   raylib [shaders] example - Render julia sets using a shader.
+*
+*   NOTE: This example requires raylib OpenGL 3.3 or ES2 versions for shaders support,
+*         OpenGL 1.1 does not support shaders, recompile raylib to OpenGL 3.3 version.
+*
+*   NOTE: Shaders used in this example are #version 330 (OpenGL 3.3).
+*
+*   This example has been created using raylib 2.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Author: eggmund (https://github.com/eggmund)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include <string.h> // For memcpy
+
+// Speed when using auto
+const float AUTO_SPEED = 0.0005;
+
+// A few good julia sets
+const float POINTS_OF_INTEREST[6][2] =
+{ 
+    {-0.348827, 0.607167},
+    {-0.786268, 0.169728},
+    {-0.8, 0.156},
+    {0.285, 0.0},
+    {-0.835, -0.2321},
+    {-0.70176, -0.3842},
+};
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 1280;
+    int screenHeight = 720;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shaders] example - julia set renderer");
+
+    // If julia set is rendered for this frame.
+    bool rendered = false;
+
+    bool showControls = true;
+
+    // Multiplier of speed to change c value. Set to 3 to start off with.
+    int incrementSpeed = 3;
+
+    // Offset and zoom to draw the julia set at. (centered on screen and 2 times smaller)
+    float offset[2] = { -(float)screenWidth/2, -(float)screenHeight/2 }; 
+    float zoom = 1.6;
+
+    // c constant to use in z^2 + c
+    float c[2];
+    // Copy a point of interest into the c variable. 4 bytes per float (32 bits).
+    memcpy(c, &POINTS_OF_INTEREST[0], 8);
+
+    // Load julia set shader
+    // NOTE: Defining 0 (NULL) for vertex shader forces usage of internal default vertex shader
+    Shader shader = LoadShader(0, "resources/shaders/glsl330/julia_shader.fs");
+    
+    // Get variable (uniform) location on the shader to connect with the program
+    // NOTE: If uniform variable could not be found in the shader, function returns -1
+    // The location of c will be stored since we will need to change this whenever c changes
+    int cLoc = GetShaderLocation(shader, "c");
+
+    // Tell the shader what the screen dimensions, zoom, offset and c are
+    float screenDims[2] = { (float)screenWidth, (float)screenHeight };
+    SetShaderValue(shader, GetShaderLocation(shader, "screenDims"), screenDims, UNIFORM_VEC2);
+    SetShaderValue(shader, GetShaderLocation(shader, "zoom"), &zoom, UNIFORM_FLOAT);
+    SetShaderValue(shader, GetShaderLocation(shader, "offset"), offset, UNIFORM_VEC2);
+
+    SetShaderValue(shader, cLoc, c, UNIFORM_VEC2);
+    
+    // Create a RenderTexture2D to be used for render to texture
+    RenderTexture2D target = LoadRenderTexture(screenWidth, screenHeight);
+    
+    SetTargetFPS(60);                       // Set the window to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())            // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+
+        // Get input
+        //----------------------------------------------------------------------------------
+
+        // Press 0 - 4 to reset c to a point of interest.
+        if (IsKeyPressed(KEY_ONE) || IsKeyPressed(KEY_TWO) || IsKeyPressed(KEY_THREE) || IsKeyPressed(KEY_FOUR) || IsKeyPressed(KEY_FIVE) || IsKeyPressed(KEY_SIX))
+        {
+            if (IsKeyPressed(KEY_ONE))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[0], 8);
+            }
+            else if (IsKeyPressed(KEY_TWO))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[1], 8);
+            }
+            else if (IsKeyPressed(KEY_THREE))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[2], 8);
+            }
+            else if (IsKeyPressed(KEY_FOUR))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[3], 8);
+            }
+            else if (IsKeyPressed(KEY_FIVE))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[4], 8);
+            }
+            else if (IsKeyPressed(KEY_SIX))
+            {
+                memcpy(c, &POINTS_OF_INTEREST[5], 8);
+            }
+            SetShaderValue(shader, cLoc, c, UNIFORM_VEC2);
+            rendered = false;  // c value has changed, so render the set again.
+        }
+
+        // Press "r" to stop changing c
+        if (IsKeyPressed(KEY_R))
+        {
+            incrementSpeed = 0;
+        }
+
+        // Toggle whether or not to show controls
+        if (IsKeyPressed(KEY_H))
+        {
+            showControls = !showControls;
+        }
+
+        // Scroll to change c increment speed.
+        int mouseMv = GetMouseWheelMove();  // Get the amount the mouse has moved this frame
+        if (mouseMv != 0)
+        {
+            if (IsKeyDown(KEY_LEFT_SHIFT))
+            {
+                incrementSpeed += mouseMv * 10;
+            }
+            else
+            {
+                incrementSpeed += mouseMv;
+            }
+            rendered = false;
+        }
+
+        if (incrementSpeed != 0)
+        {
+            float amount = GetFrameTime() * incrementSpeed * AUTO_SPEED;
+            c[0] += amount;
+            c[1] += amount;
+
+            // Update the c value in the shader.
+            SetShaderValue(shader, cLoc, c, UNIFORM_VEC2);
+            rendered = false;
+        }
+        
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(BLACK);  // Clear the screen of the previous frame.
+            
+            // If the c value has changed, redraw the julia set using the shader, onto the render texture.
+            if (!rendered)
+            {
+                BeginTextureMode(target);   // Enable drawing to texture
+
+                    ClearBackground(BLACK); // Clear the last frame drawn on the texture.
+
+                    // Draw a rectangle in shader mode. This acts as a canvas for the shader to draw on.
+                    BeginShaderMode(shader);
+                        DrawRectangle(0, 0, screenWidth, screenHeight, BLACK);
+                    EndShaderMode();
+
+                EndTextureMode();
+
+                rendered = true; // The set is now rendered, so do not compute it again until it next changes.
+            }
+
+            // Draw the saved texture (rendered julia set).
+            DrawTextureRec(target.texture, (Rectangle){ 0, 0, target.texture.width, target.texture.height }, (Vector2){ 0, 0 }, WHITE);
+            
+            // Print information.
+            DrawText( FormatText("cx: %f\ncy: %f\nspeed: %d", c[0], c[1], incrementSpeed), 10, 10, 20, RAYWHITE );
+
+            if (showControls)
+            {
+                DrawText("Press keys 1 - 6 to change point of interest.", 10, screenHeight - 88, 20, RAYWHITE);
+                DrawText("Use the scroll wheel to auto increment the c value. Hold shift while scrolling to increase speed by 10.", 10, screenHeight - 66, 20, RAYWHITE);
+                DrawText("Press 'r' to reset speed.", 10, screenHeight - 44, 20, RAYWHITE);
+                DrawText("Press 'h' to hide these controls.", 10, screenHeight - 22, 20, RAYWHITE);
+            }
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadShader(shader);           // Unload shader
+    UnloadRenderTexture(target);    // Unload render texture
+
+    CloseWindow();                  // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}