There is a problem with rendering target switch on Raspberry Pi. SDL_SetRenderTarget() hangs if multiple renderer switch occurs.
This is a working code that prints milliseconds since application starts before and after a rendering target switch:
#include <stdio.h>
#include "SDL.h"
static SDL_Window* gameWindow = NULL;
static SDL_Renderer* windowRenderer = NULL;
static SDL_Texture* gameTexture = NULL;
static SDL_Texture* texture_1 = NULL;
static SDL_Texture* texture_2 = NULL;
static SDL_Texture* texture_3 = NULL;
static SDL_Texture* texture_4 = NULL;
static SDL_Texture* texture_5 = NULL;
static int row;
static int column;
int main()
{
// Initialize SDL Video
if (SDL_InitSubSystem(SDL_INIT_VIDEO) < 0)
{
printf("%d ms - [INFO] - SDL fails to initialize video subsystem!\n%s", SDL_GetTicks(), SDL_GetError());
return -1;
}
else
printf("%d ms - [INFO] - SDL Video was initialized fine!\n", SDL_GetTicks());
// Create window
gameWindow = SDL_CreateWindow(
"SDL Render Target Test",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
640,
480,
SDL_WINDOW_SHOWN);
windowRenderer = SDL_CreateRenderer(gameWindow, -1, SDL_RENDERER_ACCELERATED);
if (windowRenderer == NULL)
return -1;
// Set color (this format is RGBA) --> Black, Opaque
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0xff);
// Clear renderer
SDL_RenderClear(windowRenderer);
printf("Window and renderer created!\n");
gameTexture = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, 320, 240);
texture_1 = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_TARGET, 1920, 1080);
texture_2 = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_TARGET, 1920, 1080);
texture_3 = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_TARGET, 1920, 1080);
texture_4 = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_TARGET, 1920, 1080);
texture_5 = SDL_CreateTexture(windowRenderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_TARGET, 1920, 1080);
printf("Textures created!\n");
if (gameTexture == NULL || texture_1 == NULL || texture_2 == NULL || texture_3 == NULL || texture_4 == NULL || texture_5 == NULL)
{
SDL_DestroyRenderer(windowRenderer);
windowRenderer = NULL;
return -1;
}
// Set textures blend mode
SDL_SetTextureBlendMode(gameTexture, SDL_BLENDMODE_BLEND);
SDL_SetTextureBlendMode(texture_1, SDL_BLENDMODE_BLEND);
SDL_SetTextureBlendMode(texture_2, SDL_BLENDMODE_BLEND);
SDL_SetTextureBlendMode(texture_3, SDL_BLENDMODE_ADD);
SDL_SetTextureBlendMode(texture_4, SDL_BLENDMODE_BLEND);
SDL_SetTextureBlendMode(texture_5, SDL_BLENDMODE_MOD);
printf("Textures blend set!\n");
// +++ Texture 1 +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_1
SDL_SetRenderTarget(windowRenderer, texture_1);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
// Set color (this format is RGBA) --> Black, Transparent
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0x00);
// Clear texture_1
SDL_RenderClear(windowRenderer);
// Set color (this format is RGBA) --> Black, With some transparency
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0x5a); // SDL_BLENDMODE_BLEND
for (row = 0; row < 1080; row += 4)
SDL_RenderDrawLine(windowRenderer, 0, row, 1920, row);
printf("Texture 1 created!\n");
// +++ Texture 2 +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_2
SDL_SetRenderTarget(windowRenderer, texture_2);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
for (column = 0; column < 1920; column += 4)
{
// SDL_BLENDMODE_BLEND
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0xff);
SDL_RenderDrawLine(windowRenderer, column, 0, column, 1080);
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0xff, 0x00, 0x00, 0xff);
SDL_RenderDrawLine(windowRenderer, column + 1, 0, column + 1, 1080);
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0xff, 0x00, 0xff);
SDL_RenderDrawLine(windowRenderer, column + 2, 0, column + 2, 1080);
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0xff, 0xff);
SDL_RenderDrawLine(windowRenderer, column + 3, 0, column + 3, 1080);
}
printf("Texture 2 created!\n");
// +++ Texture 3 for brightness +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_3
SDL_SetRenderTarget(windowRenderer, texture_3);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0xff, 0xff, 0xff, 0xd0); // SDL_BLENDMODE_ADD
// Clear texture_3
SDL_RenderClear(windowRenderer);
printf("Texture 3 created!\n");
// +++ Combine textures to texture_5 +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_5
SDL_SetRenderTarget(windowRenderer, texture_5);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
// Set color (this format is RGBA) --> Black, Opaque
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0xff);
// Clear texture_5
SDL_RenderClear(windowRenderer);
printf("Start texture combination!\n");
// Render texture_2 to texture_5
SDL_RenderCopy(windowRenderer, texture_2, NULL, NULL);
printf("First combination done!\n");
SDL_DestroyTexture(texture_2);
// +++ Texture 4 +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_4
SDL_SetRenderTarget(windowRenderer, texture_4);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
// Set color (this format is RGBA) --> Black, Transparent
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0x00);
// Clear texture_4
SDL_RenderClear(windowRenderer);
// Set color (this format is RGBA)
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0x15); // SDL_BLENDMODE_BLEND
for (column = 0; column < 1920; column += 4)
{
SDL_RenderDrawLine(windowRenderer, column, 0, column, 1080);
}
for (row = 0; row < 1080; row += 4)
{
for (column = 1; column < 1920; column += 8)
{
SDL_RenderDrawPoint(windowRenderer, column, row);
SDL_RenderDrawPoint(windowRenderer, column + 1, row);
SDL_RenderDrawPoint(windowRenderer, column + 2, row);
SDL_RenderDrawPoint(windowRenderer, column + 3, row);
SDL_RenderDrawPoint(windowRenderer, column + 4, row + 2);
SDL_RenderDrawPoint(windowRenderer, column + 4 + 1, row + 2);
SDL_RenderDrawPoint(windowRenderer, column + 4 + 2, row + 2);
SDL_RenderDrawPoint(windowRenderer, column + 4 + 3, row + 2);
}
}
printf("Texture 4 created!\n");
// +++ Combine texture to texture_5 +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on texture_5
SDL_SetRenderTarget(windowRenderer, texture_5);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
printf("Start texture combination!\n");
// Render texture_3 to texture_5
SDL_RenderCopy(windowRenderer, texture_3, NULL, NULL);
printf("Second combination done!\n");
SDL_DestroyTexture(texture_3);
printf("Texture 5 created!\n");
// +++ Set default rendering target +++ //
printf("%d ms - [INFO] - Set renderer...\n", SDL_GetTicks());
// Set target for drawing operation on default rendering target
SDL_SetRenderTarget(windowRenderer, NULL);
printf("%d ms - [INFO] - Renderer set!\n", SDL_GetTicks());
// Set color (this format is RGBA) --> Black, Transparent
SDL_SetRenderDrawColor(windowRenderer, 0x00, 0x00, 0x00, 0x00);
// Clear default renderer
SDL_RenderClear(windowRenderer);
SDL_DestroyTexture(texture_1);
SDL_DestroyTexture(texture_4);
SDL_DestroyTexture(texture_5);
SDL_DestroyRenderer(windowRenderer);
SDL_DestroyWindow(gameWindow);
return 0;
}
This is the ouptut on Ubuntu x86:
108 ms - [INFO] - SDL Video was initialized fine!
Window and renderer created!
Textures created!
Textures blend set!
252 ms - [INFO] - Set renderer...
253 ms - [INFO] - Renderer set!
Texture 1 created!
253 ms - [INFO] - Set renderer...
254 ms - [INFO] - Renderer set!
Texture 2 created!
255 ms - [INFO] - Set renderer...
257 ms - [INFO] - Renderer set!
Texture 3 created!
257 ms - [INFO] - Set renderer...
257 ms - [INFO] - Renderer set!
Start texture combination!
First combination done!
258 ms - [INFO] - Set renderer...
258 ms - [INFO] - Renderer set!
Texture 4 created!
375 ms - [INFO] - Set renderer...
450 ms - [INFO] - Renderer set!
Start texture combination!
Second combination done!
Texture 5 created!
450 ms - [INFO] - Set renderer...
450 ms - [INFO] - Renderer set!
and this one is the result on Raspberry Pi:
94 ms - [INFO] - SDL Video was initialized fine!
Window and renderer created!
Textures created!
Textures blend set!
242 ms - [INFO] - Set renderer...
242 ms - [INFO] - Renderer set!
Texture 1 created!
243 ms - [INFO] - Set renderer...
286 ms - [INFO] - Renderer set!
Texture 2 created!
288 ms - [INFO] - Set renderer...
386 ms - [INFO] - Renderer set!
Texture 3 created!
386 ms - [INFO] - Set renderer...
386 ms - [INFO] - Renderer set!
Start texture combination!
First combination done!
396 ms - [INFO] - Set renderer...
415 ms - [INFO] - Renderer set!
Texture 4 created!
837 ms - [INFO] - Set renderer...
24786 ms - [INFO] - Renderer set!
Start texture combination!
Second combination done!
Texture 5 created!
24787 ms - [INFO] - Set renderer...
24787 ms - [INFO] - Renderer set!
The application hangs for 23 seconds!!! Any idea? Also on Ubuntu x86 there is a slowdown after message Texture 4 created! during rendering set
After further investigation I found that the problem is the use of SDL_RenderDrawPoint(). If we move Texture 4 creation at the beginning of the code the slowdown occurs after that texture creation, so after a massive use of SDL_RenderDrawPoint().
I fixed the problem passing from SDL_RenderDrawPoint() to SDL_RenderDrawPoints().
In my case it is ok because that texture is created only one time at startup and in this way we pass from 23 seconds to 200 milliseconds