/*

     File: APLDiagonalWipeRenderer.m

 Abstract:  APLDiagonalWipeRenderer subclass of APLOpenGLRenderer, renders the given source buffers to perform a diagonal wipe over the time range of the transition. 

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#import "APLDiagonalWipeRenderer.h"

#define kForegroundTrack 0

#define kBackgroundTrack 1

@interface APLDiagonalWipeRenderer ()

{

    CGPoint _diagonalEnd1;

    CGPoint _diagonalEnd2;

}

@end

@implementation APLDiagonalWipeRenderer

- (id)init

{

    self = [super init];

    return self;

}

#pragma mark Setup OpenGL & shader uniforms

- (void)quadVertexCoordinates:(GLfloat *)vertexCoordinates forFrame:(int)trackID forTweenFactor:(float)tween

{

    /*

     diagonalEnd1 and diagonalEnd2 represent the endpoints of a line which partitions the frame on screen into the two parts.

     diagonalEnd1

     ------------X-----------

     |                      |

     |                      X diagonalEnd2

     |                      |

     |                      |

     ------------------------

     The below conditionals, use the tween as a measure to determine the size of the foreground and background quads.

     */

    if (tween <= 0.5) { // The expectation here is that in half the timeRange of the transition we reach the diagonal of the frame

        _diagonalEnd2.x = 1.0;

        _diagonalEnd1.y = -1.0;

        _diagonalEnd1.x = 1.0 - tween * 4;

        _diagonalEnd2.y = -1.0 + tween * 4;

        vertexCoordinates[6] = _diagonalEnd2.x;

        vertexCoordinates[7] = _diagonalEnd2.y;

        vertexCoordinates[8] = _diagonalEnd1.x;

        vertexCoordinates[9] = _diagonalEnd1.y;

    }

    else if (tween > 0.5 && tween < 1.0) {

        if (trackID == kForegroundTrack) {

            _diagonalEnd1.x = -1.0;

            _diagonalEnd2.y = 1.0;

            _diagonalEnd2.x = 1.0 - (tween - 0.5) * 4;

            _diagonalEnd1.y = -1.0 + (tween - 0.5) * 4;

            vertexCoordinates[2] = _diagonalEnd2.x;

            vertexCoordinates[3] = _diagonalEnd2.y;

            vertexCoordinates[4] = _diagonalEnd1.x;

            vertexCoordinates[5] = _diagonalEnd1.y;

            vertexCoordinates[6] = _diagonalEnd1.x;

            vertexCoordinates[7] = _diagonalEnd1.y;

            vertexCoordinates[8] = _diagonalEnd1.x;

            vertexCoordinates[9] = _diagonalEnd1.y;

        }

        else if (trackID == kBackgroundTrack) {

            vertexCoordinates[4] = 1.0;

            vertexCoordinates[5] = 1.0;

            vertexCoordinates[6] = -1.0;

            vertexCoordinates[7] = -1.0;

        }

    }

    else if (tween >= 1.0) {

        _diagonalEnd1 = CGPointMake(1.0, -1.0);

        _diagonalEnd2 = CGPointMake(1.0, -1.0);

    }

}

- (void)renderPixelBuffer:(CVPixelBufferRef)destinationPixelBuffer usingForegroundSourceBuffer:(CVPixelBufferRef)foregroundPixelBuffer andBackgroundSourceBuffer:(CVPixelBufferRef)backgroundPixelBuffer forTweenFactor:(float)tween

{

    CGLSetCurrentContext(_currentContext);

    CGLLockContext(_currentContext);

    if (foregroundPixelBuffer != NULL || backgroundPixelBuffer != NULL) {

        CVOpenGLTextureRef foregroundTexture  = [self textureForPixelBuffer:foregroundPixelBuffer];

        CVOpenGLTextureRef backgroundTexture = [self textureForPixelBuffer:backgroundPixelBuffer];

        CVOpenGLTextureRef destTexture = [self textureForPixelBuffer:destinationPixelBuffer];

        glUseProgram(self.program);

        // Set the render transform

        GLfloat preferredRenderTransform [] = {

            self.renderTransform.a, self.renderTransform.b, self.renderTransform.tx, 0.0,

            self.renderTransform.c, self.renderTransform.d, self.renderTransform.ty, 0.0,

            0.0,                       0.0,                                     1.0, 0.0,

            0.0,                       0.0,                                     0.0, 1.0,

        };

        glUniformMatrix4fv(uniforms[UNIFORM_RENDER_TRANSFORM], 1, GL_FALSE, preferredRenderTransform);

        glBindFramebuffer(GL_FRAMEBUFFER, self.offscreenBufferHandle);

        glViewport(0, 0, (int)CVPixelBufferGetWidth(destinationPixelBuffer), (int)CVPixelBufferGetHeight(destinationPixelBuffer));

        // Y planes of foreground and background frame are used to render the Y plane of the destination frame

        glActiveTexture(GL_TEXTURE0);

        glBindTexture(CVOpenGLTextureGetTarget(foregroundTexture), CVOpenGLTextureGetName(foregroundTexture));

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        glActiveTexture(GL_TEXTURE1);

        glBindTexture(CVOpenGLTextureGetTarget(backgroundTexture), CVOpenGLTextureGetName(backgroundTexture));

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        glActiveTexture(GL_TEXTURE2);

        glBindTexture(CVOpenGLTextureGetTarget(destTexture), CVOpenGLTextureGetName(destTexture));

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // GL_NEAREST

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // GL_NEAREST

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        // Attach the destination texture as a color attachment to the off screen frame buffer

        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CVOpenGLTextureGetTarget(destTexture), CVOpenGLTextureGetName(destTexture), 0);

        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {

            NSLog(@"Failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));

            goto bail;

        }

        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

        glClear(GL_COLOR_BUFFER_BIT);

        GLfloat quadVertexData1 [] = {

            -1.0, 1.0,

            1.0, 1.0,

            -1.0, -1.0,

            1.0, -1.0,

            1.0, -1.0,

        };

        // Compute the vertex data for the foreground frame at this tween

        [self quadVertexCoordinates:quadVertexData1 forFrame:kForegroundTrack forTweenFactor:tween];

        size_t frameWidth = CVPixelBufferGetWidth(destinationPixelBuffer);

        size_t frameHeight = CVPixelBufferGetHeight(destinationPixelBuffer);

        // texture data varies from 0 -> w and 0 -> h, whereas vertex data varies from -1 -> 1

        GLfloat quadTextureData1 [] = {

            (0.5 + quadVertexData1[0]/2) * frameWidth, (0.5 + quadVertexData1[1]/2) * frameHeight,

            (0.5 + quadVertexData1[2]/2) * frameWidth, (0.5 + quadVertexData1[3]/2) * frameHeight,

            (0.5 + quadVertexData1[4]/2) * frameWidth, (0.5 + quadVertexData1[5]/2) * frameHeight,

            (0.5 + quadVertexData1[6]/2) * frameWidth, (0.5 + quadVertexData1[7]/2) * frameHeight,

            (0.5 + quadVertexData1[8]/2) * frameWidth, (0.5 + quadVertexData1[9]/2) * frameHeight,

        };

        glUniform1i(uniforms[UNIFORM_RGB], 0);

        glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, quadVertexData1);

        glEnableVertexAttribArray(ATTRIB_VERTEX);

        glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, 0, 0, quadTextureData1);

        glEnableVertexAttribArray(ATTRIB_TEXCOORD);

        // Draw the foreground frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 5);

        GLfloat quadVertexData2 [] = {

            _diagonalEnd2.x, _diagonalEnd2.y,

            _diagonalEnd1.x, _diagonalEnd1.y,

            1.0, -1.0,

            1.0, -1.0,

            1.0, -1.0,

        };

        // Compute the vertex data for the background frame at this tween 

        [self quadVertexCoordinates:quadVertexData2 forFrame:kBackgroundTrack forTweenFactor:tween];

        GLfloat quadTextureData2 [] = {

            (0.5 + quadVertexData2[0]/2) * frameWidth, (0.5 + quadVertexData2[1]/2) * frameHeight,

            (0.5 + quadVertexData2[2]/2) * frameWidth, (0.5 + quadVertexData2[3]/2) * frameHeight,

            (0.5 + quadVertexData2[4]/2) * frameWidth, (0.5 + quadVertexData2[5]/2) * frameHeight,

            (0.5 + quadVertexData2[6]/2) * frameWidth, (0.5 + quadVertexData2[7]/2) * frameHeight,

            (0.5 + quadVertexData2[8]/2) * frameWidth, (0.5 + quadVertexData2[9]/2) * frameHeight,

        };

        glUniform1i(uniforms[UNIFORM_RGB], 1);

        glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, quadVertexData2);

        glEnableVertexAttribArray(ATTRIB_VERTEX);

        glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, 0, 0, quadTextureData2);

        glEnableVertexAttribArray(ATTRIB_TEXCOORD);

        // Draw the background frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 5);

        glFlush();

    bail:

        CFRelease(foregroundTexture);

        CFRelease(backgroundTexture);

        CFRelease(destTexture);

        // Periodic texture cache flush every frame

        CVOpenGLTextureCacheFlush(self.videoTextureCache, 0);

        CGLUnlockContext(_currentContext);

        CGLSetCurrentContext(_previousContext);

    }

}

@end