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Rendering textures to textures?

Midi

Joined: 01 Sep 2014

Posts: 1

Posted: Thu Sep 11, 2014 8:34 pm

Before anyone asks, yes, I have checked Google.

I've been searching for a way to render a texture onto another texture. My problem is I need to be able to draw things to particular layers, and textures seem to only be able to draw directly to the screen or to a viewport. Whenever I look online, I just find links that lead back to the wiki page on rendering a texture to the screen. Is it possible to render a texture onto another texture without having to use surfaces and then converting to textures (which kinda defeats the point of textures in the first place, but I've actually had people tell me to do that).

mr_tawan

Joined: 13 Jan 2014

Posts: 161

Posted: Fri Sep 12, 2014 11:14 am

RenderTarget. https://wiki.libsdl.org/SDL_SetRenderTarget

Naith

Joined: 03 Jul 2014

Posts: 158

Posted: Fri Sep 12, 2014 1:01 pm

I've made a code example showing how to render a image texture ('pTexture') onto another texture ('pTargetTexture'). Code below.

Code:

#include "SDL.h"

#define WINDOW_WIDTH 640
#define WINDOW_HEIGHT 480

SDL_Window* pWindow = NULL;
SDL_Renderer* pRenderer = NULL;

SDL_Texture* pTexture = NULL;
SDL_Texture* pTargetTexture = NULL;

SDL_Event Event;

bool Running = true;

int main(int argc, char* argv[])
{
// Initialize SDL
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
   // If there was a problem initializing SDL
   SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
}

// If SDL was successfully initialized
else
{
   // Create the window
   pWindow = SDL_CreateWindow("Render To Texture", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_SHOWN);

   if(pWindow)
   {
      // Create the renderer with the render to texture option enabled
      pRenderer = SDL_CreateRenderer(pWindow, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE);

      if(pRenderer)
      {
         // Set the render draw color
         SDL_SetRenderDrawColor(pRenderer, 0xFF, 0xFF, 0xFF, SDL_ALPHA_OPAQUE);

         SDL_Surface* pSurface = NULL;
         pSurface = SDL_LoadBMP("Image.bmp");

         if(pSurface)
         {
            // Create the image texture
            pTexture = SDL_CreateTextureFromSurface(pRenderer, pSurface);

            // Destroy the temporary surface
            SDL_FreeSurface(pSurface);
         }

         // Create the target texture with the render target option enabled
         pTargetTexture = SDL_CreateTexture(pRenderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, WINDOW_WIDTH, WINDOW_HEIGHT);
      }
   }
}

while(Running)
{
   while(SDL_PollEvent(&Event))
   {
      if(Event.type == SDL_QUIT)
      {
         Running = false;
         break;
      }
   }

   // Clear the current render target
   SDL_RenderClear(pRenderer);

   // Set the target texture as the current render target
   if(pTargetTexture)
      SDL_SetRenderTarget(pRenderer, pTargetTexture);


   if(pTexture)
   {
      SDL_Rect TextureQuad = {0, 0, 0, 0};

      SDL_QueryTexture(pTexture, NULL, NULL, &TextureQuad.w, &TextureQuad.h);

      TextureQuad.x = (WINDOW_WIDTH - TextureQuad.w) / 2;
      TextureQuad.y = (WINDOW_HEIGHT - TextureQuad.h) / 2;

      // Render the image texture in the middle of the window (onto the target texture)
      SDL_RenderCopy(pRenderer, pTexture, NULL, &TextureQuad);
   }

   // Reset the render target
   SDL_SetRenderTarget(pRenderer, NULL);

   // Render the target texture
   if(pTargetTexture)
      SDL_RenderCopy(pRenderer, pTargetTexture, NULL, NULL);

   // Update the screen
   SDL_RenderPresent(pRenderer);
}

// Destroy the target texture
if(pTargetTexture)
   SDL_DestroyTexture(pTargetTexture);

// Destroy the image texture
if(pTexture)
   SDL_DestroyTexture(pTexture);

// Destroy the renderer
if(pRenderer)
{
   SDL_DestroyRenderer(pRenderer);
   pRenderer = NULL;
}

if(pWindow)
{
   // Destroy the window
   SDL_DestroyWindow(pWindow);
   pWindow = NULL;
}

// Quit SDL
SDL_Quit();

return 0;
}

Rendering textures to textures?

Pallav Nawani

Joined: 19 May 2011

Posts: 122

Location: Dehradun, India

Posted: Sun Sep 14, 2014 5:32 am

https://wiki.libsdl.org/SDL_SetRenderTarget

Pallav Nawani
IronCode Gaming Private Limited
Website:Â http://www.ironcode.com
Twitter:Â http://twitter.com/Ironcode_Gaming
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Mobile: 9997478768

On Fri, Sep 12, 2014 at 2:04 AM, Midi wrote:

Quote:

The SDL forums have moved to discourse.libsdl.org. This is just a read-only archive of the previous forums, to keep old links working.

The SDL forums have moved to discourse.libsdl.org.
This is just a read-only archive of the previous forums, to keep old links working.