From ee3be0b6d39e41f2f290fefa098db429609ec0b2 Mon Sep 17 00:00:00 2001 From: Sam Hocevar Date: Sat, 12 Nov 2011 12:15:38 +0000 Subject: [PATCH] tutorial: speed up Mandelbrot zoomer by only updating one pixel out of 4 each frame. --- test/tutorial/tut03.cpp | 74 +++++++++++++++++++++++------------------ 1 file changed, 41 insertions(+), 33 deletions(-) diff --git a/test/tutorial/tut03.cpp b/test/tutorial/tut03.cpp index f17da9b0..11934acc 100644 --- a/test/tutorial/tut03.cpp +++ b/test/tutorial/tut03.cpp @@ -37,7 +37,11 @@ public: { m_size = size; m_pixels = new u8vec4[size.x * size.y]; - m_time = 0.0f; + m_frame = 0; + m_center = 0; + m_target = f64cmplx(0.001643721971153, 0.822467633298876); + //m_target = f64cmplx(0.28693186889504513, 0.014286693904085048); + m_radius = 8.0; m_ready = false; } @@ -50,26 +54,26 @@ public: { WorldEntity::TickGame(deltams); - m_time += deltams * 0.0005f; + m_frame = (m_frame + 1) % 4; - f64cmplx center(0.001643721971153, 0.822467633298876); - //f64cmplx center(0.28693186889504513, 0.014286693904085048); - double radius = 8.0 * pow(2.0, -m_time); - double step = radius / (m_size.x > m_size.y ? m_size.x : m_size.y); + double zoom = pow(2.0, -deltams * 0.00015); + m_radius *= zoom; + m_center = (m_center - m_target) * zoom * zoom + m_target; - for (int j = 0; j < m_size.y; j++) - for (int i = 0; i < m_size.x; i++) + double step = m_radius / (m_size.x > m_size.y ? m_size.x : m_size.y); + + for (int j = m_frame / 2; j < m_size.y; j += 2) + //for (int j = ((m_frame + 1) % 4) / 2; j < m_size.y; j += 2) + for (int i = m_frame % 2; i < m_size.x; i += 2) { double const maxlen = 32; - int const colors = 16; - int const maxiter = 200; + int const maxiter = 170; f64cmplx delta(i - m_size.x / 2, j - m_size.y / 2); - f64cmplx z0 = center + step * delta; + f64cmplx z0 = m_center + step * delta; f64cmplx r0 = z0; //f64cmplx r0(0.28693186889504513, 0.014286693904085048); - //f64cmplx r0(-0.824,0.1711); //f64cmplx r0(0.001643721971153, 0.822467633298876); f64cmplx z; int iter = maxiter; @@ -79,21 +83,21 @@ public: double f = iter; double n = z.sqlen(); - /* Approximate log2(x) with x-1 because x is in [1,2]. */ - f += (log(n) * 0.5f / log(maxlen)) - 1.0f; + double k = log(n) * 0.5f / log(maxlen); + /* Approximate log2(k) in [1,2]. */ + f += (- 0.344847817623168308695977510213252644185 * k + + 2.024664188044341212602376988171727038739) * k + - 1.674876738008591047163498125918330313237; if (iter) { - double r = fmod(f, (double)colors); - if (r > (double)colors / 2) r = (double)colors - r; - double g = fmod(f * 1.3 + 4.0f, (double)colors); - if (g > (double)colors / 2) g = (double)colors - g; - double b = fmod(f * 1.7 - 8.0f, (double)colors); - if (b > (double)colors / 2) b = (double)colors - b; - - uint8_t red = 255 - r * (255.0f / (colors + 1)); - uint8_t green = 255 - g * (255.0f / (colors + 1)); - uint8_t blue = 255 - b * (255.0f / (colors + 1)); + double r = 0.5 * sin(f * 0.27 - 2.0) + 0.5; + double g = 0.5 * sin(f * 0.13 + 1.0) + 0.5; + double b = 0.5 * sin(f * 0.21) + 0.5; + + uint8_t red = r * 255.0f; + uint8_t green = g * 255.0f; + uint8_t blue = b * 255.0f; m_pixels[j * m_size.x + i] = u8vec4(red, green, blue, 0); } else @@ -119,12 +123,12 @@ public: static float const texcoords[] = { - 0.0f, 0.0f, 1.0f, 0.0f, - 1.0f, 1.0f, - 1.0f, 1.0f, - 0.0f, 1.0f, 0.0f, 0.0f, + 0.0f, 1.0f, + 0.0f, 1.0f, + 1.0f, 1.0f, + 1.0f, 0.0f, }; if (!m_ready) @@ -133,8 +137,8 @@ public: glBindTexture(GL_TEXTURE_2D, m_texid); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_size.x, m_size.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_pixels); - glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); - glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); m_shader = Shader::Create( #if !defined __CELLOS_LV2__ @@ -149,7 +153,8 @@ public: "#version 120\n" "uniform sampler2D in_Texture;\n" "void main(void) {" - " gl_FragColor = texture2D(in_Texture, gl_TexCoord[0].xy);" + " vec2 coord = gl_TexCoord[0].xy;" + " gl_FragColor = texture2D(in_Texture, coord);" "}" #else "void main(float4 in_Position : POSITION," @@ -248,8 +253,11 @@ private: GLuint m_tco; #endif int m_vertexattrib, m_texattrib; - float m_time; + int m_frame; bool m_ready; + + f64cmplx m_center, m_target; + double m_radius; }; int main() @@ -261,7 +269,7 @@ int main() Application app("Tutorial 3: Fractal", ivec2(640, 480), 60.0f); new DebugFps(5, 5); - new Fractal(ivec2(1280, 960)); + new Fractal(ivec2(640, 480)); app.Run();