# OpenGL Help me optimize my draw routine

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I'm making a 2d sidescroller with SDL and Opengl. When I have 2 layers(Main layer and 1 parallax) it runs fine. When I add one more layer it starts getting slow. I'm a newb at opengl and I'm pretty sure my drawing routine can be made alot faster.
void Csprite::Draw(Ctexturemanager TextManager) {
glBindTexture(GL_TEXTURE_2D, TextManager.textures[texture].TextureID);
glTranslatef(int(x+width/2),int(y+height/2), 0);
glRotatef(rotate,0,0,1);
glScalef(scalex,scaley,1);
glTranslatef(-width/2, -height/2, 0);

srcx = int((currentframe % cols) * width);
srcy = int((currentframe / cols) * height);
srcwidth = srcx+width;
srcheight = srcy+height;

glTexCoord2f(srcx/TextManager.textures[texture].Width,1+(1-srcy/TextManager.textures[texture].Height)); glVertex2f(0, 0);
glTexCoord2f(srcwidth/TextManager.textures[texture].Width,1+(1-srcy/TextManager.textures[texture].Height)); glVertex2f(width, 0);
glTexCoord2f(srcwidth/TextManager.textures[texture].Width,1+1-(srcheight/TextManager.textures[texture].Height)); glVertex2f(width, height);
glTexCoord2f(srcx/TextManager.textures[texture].Width,1+1-(srcheight/TextManager.textures[texture].Height)); glVertex2f(0, height);
glEnd();
}

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Without enough time to help, all i can offer is that you find some way to cut down on the divisions and multiplications.

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When loading a tileset, you need to have members of your tileset class (i'm assuming your sprite class is a type of tileset as sprites generally have multiple frames) which hold some static variables. Since OpenGL textures are on a scale of 0.0 to 1.0, you'd do good to find the literal width/height of ecah tile by translating like so:

	ImgWidth = (float)Width / (float)info.Width;	ImgHeight = (float)Height / (float)info.Height;

(Width/Height being your tile width/height, and info.Width/Height being the image width/height). You should also store the ammount of tiles per row in your class, as well as the total ammount of tiles.

Its also good for you to store the width and height of each tile in literal pixels for later reference.

Then when you draw your actuial tile, you first find out which tile on the tileset your using like so:

	TileX = TileNum % TilesPerRow;	TileY = TileNum / TilesPerRow;

TileNum being the 0-whatever tilenumber in the tileset, and tilesperrow being just that.

After that, you can easily draw your tile on the actuial screen like so:

	glTexCoord2f((TileX*ImgWidth)        , (TileY*ImgHeight))    ; glVertex3f( X                   , Y,  0);		glTexCoord2f(((TileX+1)*ImgWidth), (TileY*ImgHeight))    ; glVertex3f( X+ActuialTileWidth, Y,  0);		glTexCoord2f(((TileX+1)*ImgWidth), ((TileY+1)*ImgHeight)); glVertex3f( X+ActuialTileWidth, Y+ActuialTileHeight,  0);		glTexCoord2f((TileX*ImgWidth)    , ((TileY+1)*ImgHeight)); glVertex3f( X                   , Y+ActuialTileHeight,  0);	glEnd();

(ImgWidth/Height being the literal width/height on that 0.0-1.0 scale, X/Y being the literal screen coords).

I should also note that in the above its assuming a non-standard Top-Left origin, as that is my personal preference ;)

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This is the tonemapping code:
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This is with the uncharted tonemapping:
Which makes the image a lot darker.
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void main() { vec3 color = texture2D(texture_diffuse, vTexcoord).rgb; color = Uncharted2Tonemap(color); //gamma correction (use only if not done in tonemapping code) color = gammaCorrection(color); outputF = vec4(color,1.0f); } Now, from my understanding is that tonemapping should bring the range down from HDR to 0-1.
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Here is part of my PlayerAxis class:

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public void keyPressed(KeyEvent e) { if (e.getKeyCode()== KeyEvent.VK_ESCAPE) { System.exit(0); //player move } else if (e.getKeyCode()== KeyEvent.VK_W) { //front //moveAmount[2] += -0.1f; player.playerMoving(0, 0, 1); } else if (e.getKeyCode()== KeyEvent.VK_S) { //back //moveAmount[2] += 0.1f; player.playerMoving(0, 0, -1); } else if (e.getKeyCode()== KeyEvent.VK_A) { //left //moveAmount[0] += -0.1f; player.playerMoving(-1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_D) { //right //moveAmount[0] += 0.1f; player.playerMoving(1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_E) { //moveAmount[0] += 0.1f; player.playerMoving(0, 1, 0); } else if (e.getKeyCode()== KeyEvent.VK_Q) { //moveAmount[0] += 0.1f; player.playerMoving(0, -1, 0); //camera move } else if (e.getKeyCode()== KeyEvent.VK_I) { //up player.cameraMoving(1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_K) { //down player.cameraMoving(-1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_L) { //right player.cameraMoving(-1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_J) { //left player.cameraMoving(1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_O) { //right round player.cameraMoving(-1, "z"); } else if (e.getKeyCode()== KeyEvent.VK_U) { //left round player.cameraMoving(1, "z"); } }
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So, i'm currently trying to implement an SSAO shader from THIS tutorial and i'm running into a few issues here.
Now, this SSAO method requires view space positions and normals. I'm storing the normals in my deferred renderer in world-space so i had to do a conversion and reconstruct the position from the depth buffer.
And something there goes horribly wrong (which has probably to do with worldspace to viewspace transformations).
(here is the full shader source code if someone wants to take a look at it)
Now, i suspect that the normals are the culprit.
vec3 normal = ((uNormalViewMatrix*vec4(normalize(texture2D(sNormals, vTexcoord).rgb),1.0)).xyz); "sNormals" is a 2D texture which stores the normals in world space in a RGB FP16 buffer.
Now i can't use the camera viewspace matrix to transform the normals into viewspace as the cameras position isn't set at (0,0,0), thus skewing the result.
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• Hi,
I'm trying mix two textures using own shader system, but I have a problem (I think) with uniforms.
To debug I use RenderDocs, but I did not receive good results. In the first attachment is my result, in the second attachment is what should be.
PS. I base on this tutorial https://learnopengl.com/Getting-started/Textures.

• I'm having issues loading textures, as I'm clueless on how to handle / load images maybe I missing something, but the past few days I just google a lot to try to find a solution. Well theres two issues I think, one I'm using Kotlin Native (EAP) and OpenGL wrapper / STB image, so I'm not quite sure wheres the issue, if someone with more experience could give me some hints on how to solve this issue?
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Regards

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