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• ### Similar Content

• By Elwin
So I've started in learning OpenGL , then I found the NeHe website and its Legacy Tutorials  (here is the link  http://nehe.gamedev.net/tutorial/lessons_01__05/22004/ ).But the problem is that I can't download any   examples of code ( neither C code examples nor any other language ) .As you see it is impossible to download http://nehe.gamedev5.net/data/lessons/pelles_c/lesson01.zip . Does anyone has expamles of C code of this lessons ?  And the second question. If I prefer coding on C , should I choose GLUT but not an OpenGL ?
• By elect
Hi,
ok, so, we are having problems with our current mirror reflection implementation.
At the moment we are doing it very simple, so for the i-th frame, we calculate the reflection vectors given the viewPoint and some predefined points on the mirror surface (position and normal).
Then, using the least squared algorithm, we find the point that has the minimum distance from all these reflections vectors. This is going to be our virtual viewPoint (with the right orientation).
After that, we render offscreen to a texture by setting the OpenGL camera on the virtual viewPoint.
And finally we use the rendered texture on the mirror surface.
So far this has always been fine, but now we are having some more strong constraints on accuracy.
What are our best options given that:
- we have a dynamic scene, the mirror and parts of the scene can change continuously from frame to frame
- we have about 3k points (with normals) per mirror, calculated offline using some cad program (such as Catia)
- all the mirror are always perfectly spherical (with different radius vertically and horizontally) and they are always convex
- a scene can have up to 10 mirror
- it should be fast enough also for vr (Htc Vive) on fastest gpus (only desktops)

Looking around, some papers talk about calculating some caustic surface derivation offline, but I don't know if this suits my case
Also, another paper, used some acceleration structures to detect the intersection between the reflection vectors and the scene, and then adjust the corresponding texture coordinate. This looks the most accurate but also very heavy from a computational point of view.

Other than that, I couldn't find anything updated/exhaustive around, can you help me?

• Hello all,
I am currently working on a game engine for use with my game development that I would like to be as flexible as possible.  As such the exact requirements for how things should work can't be nailed down to a specific implementation and I am looking for, at least now, a default good average case scenario design.
Here is what I have implemented:
Deferred rendering using OpenGL Arbitrary number of lights and shadow mapping Each rendered object, as defined by a set of geometry, textures, animation data, and a model matrix is rendered with its own draw call Skeletal animations implemented on the GPU.   Model matrix transformation implemented on the GPU Frustum and octree culling for optimization Here are my questions and concerns:
Doing the skeletal animation on the GPU, currently, requires doing the skinning for each object multiple times per frame: once for the initial geometry rendering and once for the shadow map rendering for each light for which it is not culled.  This seems very inefficient.  Is there a way to do skeletal animation on the GPU only once across these render calls? Without doing the model matrix transformation on the CPU, I fail to see how I can easily batch objects with the same textures and shaders in a single draw call without passing a ton of matrix data to the GPU (an array of model matrices then an index for each vertex into that array for transformation purposes?) If I do the matrix transformations on the CPU, It seems I can't really do the skinning on the GPU as the pre-transformed vertexes will wreck havoc with the calculations, so this seems not viable unless I am missing something Overall it seems like simplest solution is to just do all of the vertex manipulation on the CPU and pass the pre-transformed data to the GPU, using vertex shaders that do basically nothing.  This doesn't seem the most efficient use of the graphics hardware, but could potentially reduce the number of draw calls needed.

Really, I am looking for some advice on how to proceed with this, how something like this is typically handled.  Are the multiple draw calls and skinning calculations not a huge deal?  I would LIKE to save as much of the CPU's time per frame so it can be tasked with other things, as to keep CPU resources open to the implementation of the engine.  However, that becomes a moot point if the GPU becomes a bottleneck.

• Hello!
I would like to introduce Diligent Engine, a project that I've been recently working on. Diligent Engine is a light-weight cross-platform abstraction layer between the application and the platform-specific graphics API. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common front-end for all supported platforms and provides interoperability with underlying native API. Shader source code converter allows shaders authored in HLSL to be translated to GLSL and used on all platforms. Diligent Engine supports integration with Unity and is designed to be used as a graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. It is distributed under Apache 2.0 license and is free to use. Full source code is available for download on GitHub.
Features:
True cross-platform Exact same client code for all supported platforms and rendering backends No #if defined(_WIN32) ... #elif defined(LINUX) ... #elif defined(ANDROID) ... No #if defined(D3D11) ... #elif defined(D3D12) ... #elif defined(OPENGL) ... Exact same HLSL shaders run on all platforms and all backends Modular design Components are clearly separated logically and physically and can be used as needed Only take what you need for your project (do not want to keep samples and tutorials in your codebase? Simply remove Samples submodule. Only need core functionality? Use only Core submodule) No 15000 lines-of-code files Clear object-based interface No global states Key graphics features: Automatic shader resource binding designed to leverage the next-generation rendering APIs Multithreaded command buffer generation 50,000 draw calls at 300 fps with D3D12 backend Descriptor, memory and resource state management Modern c++ features to make code fast and reliable The following platforms and low-level APIs are currently supported:
Windows Desktop: Direct3D11, Direct3D12, OpenGL Universal Windows: Direct3D11, Direct3D12 Linux: OpenGL Android: OpenGLES MacOS: OpenGL iOS: OpenGLES API Basics
Initialization
The engine can perform initialization of the API or attach to already existing D3D11/D3D12 device or OpenGL/GLES context. For instance, the following code shows how the engine can be initialized in D3D12 mode:
#include "RenderDeviceFactoryD3D12.h" using namespace Diligent; // ...  GetEngineFactoryD3D12Type GetEngineFactoryD3D12 = nullptr; // Load the dll and import GetEngineFactoryD3D12() function LoadGraphicsEngineD3D12(GetEngineFactoryD3D12); auto *pFactoryD3D11 = GetEngineFactoryD3D12(); EngineD3D12Attribs EngD3D12Attribs; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[0] = 1024; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[1] = 32; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[2] = 16; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[3] = 16; EngD3D12Attribs.NumCommandsToFlushCmdList = 64; RefCntAutoPtr<IRenderDevice> pRenderDevice; RefCntAutoPtr<IDeviceContext> pImmediateContext; SwapChainDesc SwapChainDesc; RefCntAutoPtr<ISwapChain> pSwapChain; pFactoryD3D11->CreateDeviceAndContextsD3D12( EngD3D12Attribs, &pRenderDevice, &pImmediateContext, 0 ); pFactoryD3D11->CreateSwapChainD3D12( pRenderDevice, pImmediateContext, SwapChainDesc, hWnd, &pSwapChain ); Creating Resources
Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. To create a buffer, you need to populate BufferDesc structure and call IRenderDevice::CreateBuffer(). The following code creates a uniform (constant) buffer:
BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); Similar, to create a texture, populate TextureDesc structure and call IRenderDevice::CreateTexture() as in the following example:
TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); Initializing Pipeline State
Diligent Engine follows Direct3D12 style to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.)
To create a shader, populate ShaderCreationAttribs structure. An important member is ShaderCreationAttribs::SourceLanguage. The following are valid values for this member:
SHADER_SOURCE_LANGUAGE_DEFAULT  - The shader source format matches the underlying graphics API: HLSL for D3D11 or D3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL  - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. See shader converter for details. SHADER_SOURCE_LANGUAGE_GLSL  - The shader source is in GLSL. There is currently no GLSL to HLSL converter. To allow grouping of resources based on the frequency of expected change, Diligent Engine introduces classification of shader variables:
Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. This post describes the resource binding model in Diligent Engine.
The following is an example of shader initialization:
To create a pipeline state object, define instance of PipelineStateDesc structure. The structure defines the pipeline specifics such as if the pipeline is a compute pipeline, number and format of render targets as well as depth-stencil format:
// This is a graphics pipeline PSODesc.IsComputePipeline = false; PSODesc.GraphicsPipeline.NumRenderTargets = 1; PSODesc.GraphicsPipeline.RTVFormats[0] = TEX_FORMAT_RGBA8_UNORM_SRGB; PSODesc.GraphicsPipeline.DSVFormat = TEX_FORMAT_D32_FLOAT; The structure also defines depth-stencil, rasterizer, blend state, input layout and other parameters. For instance, rasterizer state can be defined as in the code snippet below:
// Init rasterizer state RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; //RSDesc.MultisampleEnable = false; // do not allow msaa (fonts would be degraded) RasterizerDesc.AntialiasedLineEnable = False; When all fields are populated, call IRenderDevice::CreatePipelineState() to create the PSO:
Shader resource binding in Diligent Engine is based on grouping variables in 3 different groups (static, mutable and dynamic). Static variables are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. They are bound directly to the shader object:

m_pPSO->CreateShaderResourceBinding(&m_pSRB); Dynamic and mutable resources are then bound through SRB object:
m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "tex2DDiffuse")->Set(pDiffuseTexSRV); m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); The difference between mutable and dynamic resources is that mutable ones can only be set once for every instance of a shader resource binding. Dynamic resources can be set multiple times. It is important to properly set the variable type as this may affect performance. Static variables are generally most efficient, followed by mutable. Dynamic variables are most expensive from performance point of view. This post explains shader resource binding in more details.
Setting the Pipeline State and Invoking Draw Command
Before any draw command can be invoked, all required vertex and index buffers as well as the pipeline state should be bound to the device context:
// Clear render target const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); m_pContext->SetPipelineState(m_pPSO); Also, all shader resources must be committed to the device context:
m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); When all required states and resources are bound, IDeviceContext::Draw() can be used to execute draw command or IDeviceContext::DispatchCompute() can be used to execute compute command. Note that for a draw command, graphics pipeline must be bound, and for dispatch command, compute pipeline must be bound. Draw() takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); Tutorials and Samples
The GitHub repository contains a number of tutorials and sample applications that demonstrate the API usage.

AntTweakBar sample demonstrates how to use AntTweakBar library to create simple user interface.

Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to textures, using compute shaders and unordered access views, etc.

The repository includes Asteroids performance benchmark based on this demo developed by Intel. It renders 50,000 unique textured asteroids and lets compare performance of D3D11 and D3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

Integration with Unity
Diligent Engine supports integration with Unity through Unity low-level native plugin interface. The engine relies on Native API Interoperability to attach to the graphics API initialized by Unity. After Diligent Engine device and context are created, they can be used us usual to create resources and issue rendering commands. GhostCubePlugin shows an example how Diligent Engine can be used to render a ghost cube only visible as a reflection in a mirror.

• By Yxjmir
I'm trying to load data from a .gltf file into a struct to use to load a .bin file. I don't think there is a problem with how the vertex positions are loaded, but with the indices. This is what I get when drawing with glDrawArrays(GL_LINES, ...):

Also, using glDrawElements gives a similar result. Since it looks like its drawing triangles using the wrong vertices for each face, I'm assuming it needs an index buffer/element buffer. (I'm not sure why there is a line going through part of it, it doesn't look like it belongs to a side, re-exported it without texture coordinates checked, and its not there)
I'm using jsoncpp to load the GLTF file, its format is based on JSON. Here is the gltf struct I'm using, and how I parse the file:
glBindVertexArray(g_pGame->m_VAO);
glDrawElements(GL_LINES, g_pGame->m_indices.size(), GL_UNSIGNED_BYTE, (void*)0); // Only shows with GL_UNSIGNED_BYTE
glDrawArrays(GL_LINES, 0, g_pGame->m_vertexCount);
So, I'm asking what type should I use for the indices? it doesn't seem to be unsigned short, which is what I selected with the Khronos Group Exporter for blender. Also, am I reading part or all of the .bin file wrong?
Test.gltf
Test.bin

# OpenGL Draw wide texture between two points

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Hi all.
Trying to implement effect of lazer shooting using 2D sprite in OpenGl with gluOrtho2D(0, width, height, 0).

What i want to have:
draw wide texture (128x26) between points A and B within 1 sec,
the coordinates of the points A and B are changed during this seccond. The texture must be dynamically scaled by weight(depends on the distance between A and B), but height must be constant(in my case 16 pixels)

The main purpose is to keep algorithm as simple as possible:
for example i want to avoid to use glRotatef function, because i have to calculate angle between A and B within game loop. I believe that exist some simple resolution of my problem. What i want is to draw wide texture between two points.

My last approach is following:
x, y - coordinate of point A
xt, yt - coordinate of point B
h - desired texture height

def draw_tex_inRect((x, y), (xt, yt), h, tex):    glBindTexture(GL_TEXTURE_2D, tex)    # Send four vertices to draw a quad    glBegin(GL_QUADS)    glTexCoord2f(0, 0); glVertex2f(x - h/2, y - h/2)    glTexCoord2f(1, 0); glVertex2f(xt + h/2, yt - h/2)    glTexCoord2f(1, 1); glVertex2f(xt + h/2, yt + h/2)    glTexCoord2f(0, 1); glVertex2f(x - h/2, y + h/2)    glEnd()

But disadvantage of this method is: when angle between A and B is aimed to 90 or 270 then texture height is aimed to 0. This problem is illustrated on the picture below
Good variant:
http://i47.tinypic.com/1z7w1z.jpg
As u may see here angle is aimed to 0
http://i46.tinypic.com/21cwmb.jpg
As u may see here angle is aimed to 90(270), and that is why texture height is decreasing(effect that i want to avoid)

def resize(width, height):    glViewport(0,0,width, height)    glMatrixMode(GL_PROJECTION)    glLoadIdentity()    gluOrtho2D(0, width, height, 0)    glDisable(GL_DEPTH_TEST)    glMatrixMode(GL_MODELVIEW)    glLoadIdentity()

Maybe someone have any idea how to implement this correctly?

[Edited by - diverlin on July 6, 2010 12:53:54 PM]

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Right I see.

You have to rotate the lazer beam quad, either by applying a rotational matrix or by doing the math yourself.

Im going now work now, Ill post some example code on the second option in a bit :)

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Hi empirical2
Quote:
 Original post by empirical2You have to rotate the lazer beam quad, either by applying a rotational matrix or by doing the math yourself.

Yes, indeed. Sorry for my "many words", it's hard to generate strict question if you are beginner in graphic and + u English is not native language. Anyway, thanks for diving into my problem and "my" not brilliant English :D

Quote:
 Im going now work now, Ill post some example code on the second option in a bit :)

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The easiest would be something like this (C++) off the top of my head....

I have not tested this and a suck at math so if its at the wrong angles try switching x-xt to xt-x (same with y-yt)

float XL=x-xt,YL=y-ytfloat Angle=atan2(XL,YL);float Len=sqrt((XL*XL)+(YL*YL));glPushMatrix();glRotate(Angle,0,0,1.0f);glTranslate(x,y,0);glBegin(GL_QUADS)glTexCoord2f(0, 0); glVertex2f(- h/2,0);glTexCoord2f(1, 0); glVertex2f(h/2, Len);glTexCoord2f(1, 1); glVertex2f(h/2, Len);glTexCoord2f(0, 1); glVertex2f(- h/2, 0);glEnd();glPopMatrix();

This is for if you want to do the math in your own application. Now this one I have just tested (with lines) so should work

	//Get the distance between the points on each axis	float LX=x-xt;	float LY=yt-y;	//Calculate the length the quad needs to be and the sine & cosine values required for calculate the rotation of each point	float Len=sqrt((LX*LX)+(LY*LY));	float TheSin=LX/Len;	float TheCos=LY/Len;	float h=5;	//Matrix math is hard :( 	float X1=(-h*TheCos) - (0*TheSin)+x,Y1=(-h*TheSin) + (0*TheCos)+y;	float X2=( h*TheCos) - (0*TheSin)+x,Y2=( h*TheSin) + (0*TheCos)+y;	float X3=( h*TheCos) - (Len*TheSin)+x,Y3=( h*TheSin) + (Len*TheCos)+y;	float X4=(-h*TheCos) - (Len*TheSin)+x,Y4=(-h*TheSin) + (Len*TheCos)+y;	//Draw the quad!glBegin(GL_QUADS)glTexCoord2f(0, 0); glVertex2f(X1,Y1,0);glTexCoord2f(0, 0); glVertex2f(X2,Y2,0);glTexCoord2f(0, 0); glVertex2f(X3,Y3,0);glTexCoord2f(0, 0); glVertex2f(X4,Y4,0);glEnd(GL_QUADS)

HTH

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Quote:
 for example i want to avoid to use glRotatef function, because i have to calculate angle between A and B within game loop.
Why do you want to avoid calculating the angle within the game loop?

There are other ways you could do it though, if need be. One would be to construct a basis from the vectors A and B, and then compute the corners of the quad manually from this basis. (Ask if you need further details.)

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You don't even need trigonometry: since angles are 90 degrees, all you have to do is swap the x,y coordinates to rotate.

rotate 90 deg CW: x,y -> y,-x
rotate 90 deg CCW: x,y ->-y,x

So you calculate the direction vector, you normalize it, then you rotate it in both directions and multiply it with the height/thickness of the beam. You add the two vectors to both ends of the beam, and you have your quad.

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Quote:
 Original post by szecsYou don't even need trigonometry: since angles are 90 degrees, all you have to do is swap the x,y coordinates to rotate.
Where did the OP say the angles were multiples of 90? (I can't find it anywhere in his posts...)

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Quote:
Original post by jyk
Quote:
 Original post by szecsYou don't even need trigonometry: since angles are 90 degrees, all you have to do is swap the x,y coordinates to rotate.
Where did the OP say the angles were multiples of 90? (I can't find it anywhere in his posts...)

The OP is speaking about a rotated rectangle no? And for some reason, the OP doesn't want to use rotation to make the quad.

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Oh, I see. (I thought you meant that the beams themselves were only oriented at 90-degree intervals.)

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empirical2 it works! Thanks a lot
Quote:
 Original post by empirical2The easiest would be something like this (C++) off the top of my head....I have not tested this and a suck at math so if its at the wrong angles try switching x-xt to xt-x (same with y-yt)

I was used the first variant of you code and adapt it to my program.
I didn't check the second method because it has many of mathematic (python don't like this)

def draw_tex_inRect((x, y), (xt, yt), h, tex):    XL= xt - x    YL= yt - y    Angle=atan2(YL,XL) * 57.295779    Len=sqrt((XL*XL)+(YL*YL))    glBindTexture(GL_TEXTURE_2D, tex)    glPushMatrix()    glTranslatef(x,y,0)    glRotatef(Angle,0,0,1.0)    glBegin(GL_QUADS)    glTexCoord2f(0, 0); glVertex2f(0,  -h/2 )    glTexCoord2f(1, 0); glVertex2f(Len,-h/2 )    glTexCoord2f(1, 1); glVertex2f(Len, h/2)    glTexCoord2f(0, 1); glVertex2f(0,  h/2)    glEnd()    glPopMatrix()

And i also changed from gluOrtho2D(0, width, height, 0) to gluOrtho2D(0, width, 0, height)
def resize(width, height):    glMatrixMode(GL_PROJECTION)    glLoadIdentity()    gluOrtho2D(0, width, 0, height)    glDisable(GL_DEPTH_TEST)    glMatrixMode(GL_MODELVIEW)    glLoadIdentity()

Quote:
 Why do you want to avoid calculating the angle within the game loop?

In my game i hope to use this effect very frequently(for example fire up to 100 space ships). I am using python as the programming language. As known this language is slow in mathematic(for my game it's OK, because for most objects move i use pre-calculated lists of coordinates). So i wanted to think about optimization. My thought was that exist the easiest way to draw rotated texture without angle calculation, for example using coordinates of two points A and B (the texture_width will me in Vector AB, and texture_height all time is constant and perpendicular to Vector AB). But recently i got new point(i will be able to perform length and angle re-freshing not for each frame, let's say once per 5-7 frames. This should not kill perfomance and still provide good looking :).

Quote:
 There are other ways you could do it though, if need be. One would be to construct a basis from the vectors A and B, and then compute the corners of the quad manually from this basis. (Ask if you need further details.)

I may have wrong understanding but is this the same code as empirical2 provides?