/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 APLCrossDissolveRenderer subclass of APLOpenGLRenderer, renders the given source buffers to perform a cross dissolve over the time range of the transition.

 */

#import "APLCrossDissolveRenderer.h"

@implementation APLCrossDissolveRenderer

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

{

    [EAGLContext setCurrentContext:self.currentContext];

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

        CVOpenGLESTextureRef foregroundLumaTexture  = [self lumaTextureForPixelBuffer:foregroundPixelBuffer];

        CVOpenGLESTextureRef foregroundChromaTexture = [self chromaTextureForPixelBuffer:foregroundPixelBuffer];

        CVOpenGLESTextureRef backgroundLumaTexture = [self lumaTextureForPixelBuffer:backgroundPixelBuffer];

        CVOpenGLESTextureRef backgroundChromaTexture = [self chromaTextureForPixelBuffer:backgroundPixelBuffer];

        CVOpenGLESTextureRef destLumaTexture = [self lumaTextureForPixelBuffer:destinationPixelBuffer];

        CVOpenGLESTextureRef destChromaTexture = [self chromaTextureForPixelBuffer:destinationPixelBuffer];

        glUseProgram(self.programY);

        // 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_Y], 1, GL_FALSE, preferredRenderTransform);

        glBindFramebuffer(GL_FRAMEBUFFER, self.offscreenBufferHandle);

        glViewport(0, 0, (int)CVPixelBufferGetWidthOfPlane(destinationPixelBuffer, 0), (int)CVPixelBufferGetHeightOfPlane(destinationPixelBuffer, 0));

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

        glActiveTexture(GL_TEXTURE0);

        glBindTexture(CVOpenGLESTextureGetTarget(foregroundLumaTexture), CVOpenGLESTextureGetName(foregroundLumaTexture));

        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(CVOpenGLESTextureGetTarget(backgroundLumaTexture), CVOpenGLESTextureGetName(backgroundLumaTexture));

        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);

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

        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CVOpenGLESTextureGetTarget(destLumaTexture), CVOpenGLESTextureGetName(destLumaTexture), 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,

        };

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

        GLfloat quadTextureData1 [] = {

            0.5 + quadVertexData1[0]/2, 0.5 + quadVertexData1[1]/2,

            0.5 + quadVertexData1[2]/2, 0.5 + quadVertexData1[3]/2,

            0.5 + quadVertexData1[4]/2, 0.5 + quadVertexData1[5]/2,

            0.5 + quadVertexData1[6]/2, 0.5 + quadVertexData1[7]/2,

        };

        glUniform1i(uniforms[UNIFORM_Y], 0);

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

        glEnableVertexAttribArray(ATTRIB_VERTEX_Y);

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

        glEnableVertexAttribArray(ATTRIB_TEXCOORD_Y);

        // Blend function to draw the foreground frame

        glEnable(GL_BLEND);

        glBlendFunc(GL_ONE, GL_ZERO);

        // Draw the foreground frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

        glUniform1i(uniforms[UNIFORM_Y], 1);

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

        glEnableVertexAttribArray(ATTRIB_VERTEX_Y);

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

        glEnableVertexAttribArray(ATTRIB_TEXCOORD_Y);

        // Blend function to draw the background frame

        glBlendColor(0, 0, 0, tween);

        glBlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);

        // Draw the background frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

        // Perform similar operations as above for the UV plane

        glUseProgram(self.programUV);

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

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

        glActiveTexture(GL_TEXTURE2);

        glBindTexture(CVOpenGLESTextureGetTarget(foregroundChromaTexture), CVOpenGLESTextureGetName(foregroundChromaTexture));

        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_TEXTURE3);

        glBindTexture(CVOpenGLESTextureGetTarget(backgroundChromaTexture), CVOpenGLESTextureGetName(backgroundChromaTexture));

        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);

        glViewport(0, 0, (int)CVPixelBufferGetWidthOfPlane(destinationPixelBuffer, 1), (int)CVPixelBufferGetHeightOfPlane(destinationPixelBuffer, 1));

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

        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CVOpenGLESTextureGetTarget(destChromaTexture), CVOpenGLESTextureGetName(destChromaTexture), 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);

        glUniform1i(uniforms[UNIFORM_UV], 2);

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

        glEnableVertexAttribArray(ATTRIB_VERTEX_UV);

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

        glEnableVertexAttribArray(ATTRIB_TEXCOORD_UV);

        glBlendFunc(GL_ONE, GL_ZERO);

        // Draw the foreground frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

        glUniform1i(uniforms[UNIFORM_UV], 3);

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

        glEnableVertexAttribArray(ATTRIB_VERTEX_UV);

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

        glEnableVertexAttribArray(ATTRIB_TEXCOORD_UV);

        glBlendColor(0, 0, 0, tween);

        glBlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);

        // Draw the background frame

        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

        glFlush();

    bail:

        CFRelease(foregroundLumaTexture);

        CFRelease(foregroundChromaTexture);

        CFRelease(backgroundLumaTexture);

        CFRelease(backgroundChromaTexture);

        CFRelease(destLumaTexture);

        CFRelease(destChromaTexture);

        // Periodic texture cache flush every frame

        CVOpenGLESTextureCacheFlush(self.videoTextureCache, 0);

        [EAGLContext setCurrentContext:nil];

    }

}

@end