81 lines
2.0 KiB
C++
81 lines
2.0 KiB
C++
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//
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// gif-h-demo.cpp
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// by Charlie Tangora
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// Public domain.
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// Email me : ctangora -at- gmail -dot- com
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//
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// Shows an example usage of gif.h
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//
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#include "gif.h"
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#include <math.h>
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const int width = 256;
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const int height = 256;
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uint8_t image[ width * height * 4 ];
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void SetPixel( int xx, int yy, uint8_t red, uint8_t grn, uint8_t blu )
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{
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uint8_t* pixel = &image[(yy*width+xx)*4];
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pixel[0] = red;
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pixel[1] = blu;
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pixel[2] = grn;
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pixel[3] = 255; // no alpha for this demo
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}
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void SetPixelFloat( int xx, int yy, float fred, float fgrn, float fblu )
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{
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// convert float to unorm
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uint8_t red = (uint8_t)roundf( 255.0f * fred );
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uint8_t grn = (uint8_t)roundf( 255.0f * fgrn );
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uint8_t blu = (uint8_t)roundf( 255.0f * fblu );
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SetPixel( xx, yy, red, grn, blu );
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}
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int main(int argc, const char * argv[])
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{
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const char* filename = "./MyGif.gif";
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if( argc > 1 )
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{
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filename = argv[1];
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}
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// Create a gif
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GifWriter writer = {};
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GifBegin( &writer, filename, width, height, 2, 8, true );
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for( int frame=0; frame<256; ++frame )
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{
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// Make an image, somehow
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// this is the default shadertoy - credit to shadertoy.com
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float tt = frame * 3.14159f * 2 / 255.0f;
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for( int yy=0; yy<height; ++yy )
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{
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for( int xx=0; xx<width; ++xx )
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{
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float fx = xx / (float)width;
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float fy = yy / (float)height;
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float red = 0.5f + 0.5f * cosf(tt+fx);
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float grn = 0.5f + 0.5f * cosf(tt+fy+2.f);
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float blu = 0.5f + 0.5f * cosf(tt+fx+4.f);
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SetPixelFloat( xx, yy, red, grn, blu );
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}
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}
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// Write the frame to the gif
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printf( "Writing frame %d...\n", frame );
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GifWriteFrame( &writer, image, width, height, 2, 8, true );
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}
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// Write EOF
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GifEnd( &writer );
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return 0;
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}
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