I cannot get texture coordinates to have any effect on what is rendered on screen. My texture constantly seemed to rendering from 0,0 to 1,1.
The method I am using is to send the following buffer layout: x,y,u,v (xy: vertex position and u,v texture coordinates).
However, changing the values u & v have no effect on the rendered texture.
I've removed a lot of surrounding code to try and make it easier to read, but I can post it in full if the problem isn't immediately obvious to someone.
Vertex Shader:
#version 330 core
layout(location = 0) in vec2 position;
layout(location = 1) in vec2 mytextpos;
out vec2 v_TexCoord;
uniform mat4 u_Model;
void main()
{
gl_Position = u_Model * vec4(position, 0.0f, 1.0f);
v_TexCoord = mytextpos;
}
Fragment Shader:
#version 330 core
layout(location = 0) out vec4 color;
in vec2 v_TexCoord;
uniform sampler2D u_Texture;
void main()
{
color = texture(u_Texture, v_TexCoord);
}
My Rectangle Class Constructor:
// GENERATE BUFFERS
glGenVertexArrays(1, &VertexArrayObject);
glGenBuffers(1, &VertexBufferId);
glGenBuffers(1, &IndexBufferObjectId);
Indices = {
0, 1, 2,
2, 3, 0
};
unsigned int numberOfVertices = Vertices.size();
unsigned int numberOfIndices = Indices.size();
glBindVertexArray(VertexArrayObject);
glBindBuffer(GL_ARRAY_BUFFER, VertexBufferId);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IndexBufferObjectId);
Vertices = {
0.2f, 0.0f, 0.0f, 0.5f,
1.0f, 0.0f, 1.5f, 0.5f,
1.0f, 1.0f, 1.5f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f
};
// ADD BUFFER DATA
glBufferData( GL_ARRAY_BUFFER, Vertices.size() * sizeof(float), Vertices.data(), GL_STATIC_DRAW );
// ARRANGE ATTRIBUTES
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), nullptr);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), nullptr);
glEnableVertexAttribArray(1);
glBufferData( GL_ELEMENT_ARRAY_BUFFER, numberOfIndices * sizeof(unsigned int), Indices.data(), GL_STATIC_DRAW );`
Render Function:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
GLint u_Texture = glGetUniformLocation( shader.getId(), "u_Texture" );
glUniform1i( u_Texture, 0 );
GLint u_Model = glGetUniformLocation( shader.getId(), "u_Model" );
glUniformMatrix4fv( u_Model, 1, GL_FALSE, glm::value_ptr( rect.TransformMatrix() ) );
glDrawElements(GL_TRIANGLES, rect.Indices.size(), GL_UNSIGNED_INT, nullptr);
// SWAP BUFFERS
glfwSwapBuffers( _window->WindowInstance );
glfwPollEvents();
My program runs, but my texture is mapped between 0,0 and 1,0 no matter what my vertex or u,v positions are. I would expect the texture to be interpolated between the u,v coordinates for each vertex?
You attribute setup is wrong:
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), nullptr);
This tells OpenGL that it should attach the first two floats of each vertex to the mytextpos attribute. But you actually want it to read the 3rd and 4th float. Thus you have to set the offset such that it skips the first two floats:
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)(2 * sizeof(float)));
Related
I've made a program that displays some textures depending on the given input and can rotate, resize and move the textures depending on the given input. The program works perfectly fine but when I rotate the textures the edges appear to be pixelated, like this:
Is there a way for me to smoothen out these edges?
Here are my shaders and texture classes:
texture.vs:
#version 300 es
precision mediump float;
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexCoord;
out vec3 ourColor;
out vec2 TexCoord;
uniform mat4 transform;
void main()
{
gl_Position = transform * vec4(aPos, 1.0f);
ourColor = aColor;
TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}
texture.fs
#version 300 es
precision mediump float;
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
// texture sampler
uniform sampler2D texture1;
void main()
{
FragColor = texture(texture1, TexCoord);
}
Here is my texture.cpp:
Texture::Texture(int x, int y, int w, int h, int gw, int gh)
{
pos.TL_x = _VERTICIZE_X(x, gw);
pos.TL_y = -_VERTICIZE_Y(y, gh);
pos.TR_x = _VERTICIZE_X(x + w, gw);
pos.TR_y = -_VERTICIZE_Y(y, gh);
pos.BL_x = _VERTICIZE_X(x, gw);
pos.BL_y = -_VERTICIZE_Y(y + h, gh);
pos.BR_x = _VERTICIZE_X(x + w, gw);
pos.BR_y = -_VERTICIZE_Y(y + h, gh);
}
void set_max_z(int z)
{
max_z = z;
}
int Texture::init(float ang_rad, float z)
{
shader = Shader("./src/opengl/shaders/image.vs", "./src/opengl/shaders/image.fs");
this->angle = ang_rad;
// build and compile our shader zprogram
// ------------------------------------
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[32] = {
// positions // colors // texture coords
pos.TR_x, pos.TR_y, _VERTICIZE_Z(z, max_z), 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, // top right
pos.BR_x, pos.BR_y, _VERTICIZE_Z(z, max_z), 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, // bottom right
pos.BL_x, pos.BL_y, _VERTICIZE_Z(z, max_z), 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, // bottom left
pos.TL_x, pos.TL_y, _VERTICIZE_Z(z, max_z), 1.0f, 1.0f, 1.0f, 0.0f, 0.0f // top left
};
unsigned int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
glEnable(GL_DEPTH_TEST);
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// texture coord attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
// load and create a texture
// -------------------------
// texture 1
// ----------
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
// tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
// -------------------------------------------------------------------------------------------
shader.use(); // don't forget to activate/use the shader before setting uniforms!
// either set it manually like so:
glUniform1i(glGetUniformLocation(shader.ID, "texture"), 0);
return 0;
}
void Texture::render(int w, int h, uint8_t *buffer)
{
// If having trouble doing multiple textures, add "+ index to Active Texture."
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
glGenerateMipmap(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0);
glm::mat4 transform = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
transform = glm::translate(transform, glm::vec3(0.0f, 0.0f, 0.0f));
transform = glm::rotate(transform, glm::radians(this->angle), glm::vec3(0.0f, 0.0f, 1.0f));
// get matrix's uniform location and set matrix
shader.use();
unsigned int transformLoc = glGetUniformLocation(shader.ID, "transform");
glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
}
Texture::~Texture()
{
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
}
void Texture::framebuffer_size_callback(GLFWwindow *window, int width, int height)
{
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(0, 0, width, height);
}
(_VERTICIZE just calculates points)
I'm using ubuntu, GLAD, GLFW.
This appears to be a classic example of Aliasing. We can fix this by enabling MSAA.
GLFW has an inbuilt way of doing that. Put this before you create the window:
glfwWindowHint(GLFW_SAMPLES, 4); /* if effect is not strong enough, change to 8 */
Edit -
You have to call glfwWindowHint(GLFW_SAMPLES, 4) in between glfwInit and glfwCreateWindow.
Also, in case OpenGL doesn't enable multisampling by default, do
glEnable(GL_MULTISAMPLE);
I am trying to draw a grid of velocity vectors, I expect the velocity at each grid point to be a line with a slop of 1. A slanting line, but I always end up with a vertical line. I'm not sure what I'm doing wrong. Is there something I'm overlooking?
Here is how my vertex buffer looks :
float vel_pos[6*(N+2)*(N+2)];
int index1 = 0;
for (int i=0;i<N+2;i++)
{
for (int j=0;j<N+2;j++)
{
vel_pos[index1] = float(i);
vel_pos[index1+1] = float(j);
vel_pos[index1+2] = 0.0f;
vel_pos[index1+3] = float(i) +0.5f;
vel_pos[index1+4] = float(j) + 0.5f;
vel_pos[index1+5] = 0.0f;
index1 += 6;
}
}
Here is how I am creating my VBO and VAO :
unsigned int VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
// Bind vertex array object first and then bind the vertex buffer objects
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vel_pos), vel_pos, GL_STREAM_DRAW);
GLint velAttrib = glGetAttribLocation(ourShader.ID, "aPos");
// iterpreting data from buffer
glVertexAttribPointer(velAttrib, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
Here is my vertex shader :
out vec4 vertexColor;
layout (location = 0) in vec3 aPos;
layout (location = 1) in float densitySource; /* source of density */
uniform mat4 transform;
uniform mat4 projection;
void main()
{
gl_Position = projection*transform * vec4(aPos, 1.0);
vertexColor = vec4(1, 0.0, 0.0, 1.0);
}
And here's my drawing code :
ourShader.use();
glm::mat4 trans = glm::mat4(1.0f);
trans = glm::translate(trans, glm::vec3(-0.5f, -0.5f, 0.0f));
unsigned int transformMatrixLocation = glGetUniformLocation(ourShader.ID, "transform");
glUniformMatrix4fv(transformMatrixLocation, 1, GL_FALSE, glm::value_ptr(trans));
glm::mat4 projection = glm::ortho(-10.0f, 110.0f, -1.0f, 110.0f, -1.0f, 100.0f);
unsigned int projectionMatrixLocation = glGetUniformLocation(ourShader.ID, "projection");
glUniformMatrix4fv(projectionMatrixLocation, 1, GL_FALSE, glm::value_ptr(projection));
glBindVertexArray(VAO);
glLineWidth(1.0f);
glDrawArrays(GL_LINES, 0, (N+2)*(N+2));
This is the image I get :
resulting image
The 5th parameter (stride) of glVertexAttribPointer is the offset between two vertex coordinates and not between to primitives. Since your vertex coordinates have 3 components of type float, the offset has to be 3 * sizeof(float):
glVertexAttribPointer(velAttrib, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
Because you set an offset of 6 * sizeof(float), you have skipped every 2 coordinate and have drawn lines between the points of the grid.
But note, if stride is 0, the generic vertex attributes are understood to be tightly packed in the array. This is the case, so you ca use an offset of 0:
glVertexAttribPointer(velAttrib, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
I'm trying to texture the ground with grass. Would someone mind looking through my steps to get a 2D texture to show up in 3D space? I haven't had any luck with online tutorials.
Here is my steps:
1) Call the sprite class initialization to set the vertex coordinates and uv data
void Sprite::init(vec3 bottomleft, vec3 topLeft, vec3 topRight, vec3 bottomRight, std::string texturePath)
{
_texture = ImageLoader::loadPNG(texturePath);
_points = { bottomleft.x, bottomleft.y, bottomleft.z, topLeft.x, topLeft.y, topLeft.z, topRight.x, topRight.y, topRight.z, topRight.x, topRight.y, topRight.z, bottomRight.x, bottomRight.y, bottomRight.z, bottomleft.x, bottomleft.y, bottomleft.z };
_uv = { 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f };
}
I use the uniform sampler and activate the texture
//draw ground texture
glUniform1i(samplerLocation, 0);
glActiveTexture(GL_TEXTURE0);
_grassTexture.draw();
The draw function is implemented as follows, which puts the data in the buffer and draws the triangle:
void Sprite::draw()
{
if (_vboID == 0)
{
glGenBuffers(1, &_vboID);
}
glBindTexture(GL_TEXTURE_2D, _texture.id);
glBindBuffer(GL_ARRAY_BUFFER, _vboID);
glBufferData(GL_ARRAY_BUFFER, _points.size() * sizeof(float) + _uv.size() * sizeof(float), nullptr, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, _points.size() * sizeof(float), &_points.front());
glBufferSubData(GL_ARRAY_BUFFER, _points.size() * sizeof(float), _uv.size() * sizeof(float), &_uv.front());
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
//position attribute pointer
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, &_points.front());
//uv attribute pointer
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, &_uv.front());
glDrawArrays(GL_TRIANGLES, 0, 6);
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
The vertex shader:
#version 400
in vec4 vertexPosition;
in vec2 vertexUV;
out vec4 fragmentColor;
out vec2 fragmentUV;
uniform mat4 MVP;
uniform vec4 COLOR;
void main()
{
gl_Position = MVP * vertexPosition;
fragmentColor = COLOR;
fragmentUV = vec2(vertexUV.x, 1.0 - vertexUV.y);
}
and fragment shader:
#version 400
in vec4 fragmentColor;
in vec2 fragmentUV;
out vec4 fragColor;
uniform sampler2D SAMPLER;
void main()
{
vec4 textureColor = texture(SAMPLER, fragmentUV);
fragColor = textureColor * fragmentColor;
}
At this point, nothing displays in the screen. I do know that the textureColor in the fragment shader is green, so it appears the uniform is being set correctly. My best guess is that I'm either missing a texture initialization step or am not filling the buffer correctly.
I think there's a problem with the pointer parameter in your calls to glVertexAttribPointer. You're passing the address of your _points and _uv arrays, but you should be passing the offset relative to the base of your vbo.
Try:
//position attribute pointer
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
//uv attribute pointer
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, (const GLvoid*)(_points.size() * sizeof(float)));
I'm trying to implement instancing into my 2d Game Engine so that it can support particle systems without losing any performance. My class, ISprite, is derived from a working Sprite class. I just went through and removed all the functionality affecting single sprites and replaced it with an instancing plan in mind. Unfortunately, nothing is drawing on the screen.
Here is the relevant information:
Vertex Shader
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec2 texCoords;
layout (location = 2) in vec4 colorSource;
layout (location = 3) in mat4 transform;
out vec2 TexCoords;
out vec4 Color;
uniform mat4 uniformView;
uniform mat4 uniformProjection;
void main()
{
gl_Position = uniformProjection * uniformView * transform * vec4(position, 1.0f);
TexCoords = texCoords;
Color = colorSource;
}
Fragment Shader
#version 330 core
in vec2 TexCoords;
in vec4 Color;
out vec4 color;
uniform sampler2D Texture;
uniform vec4 uniformColor;
void main()
{
vec4 texColor = texture(Texture, TexCoords) * Color;
if(texColor.a < 0.1)
discard;
color = texColor;
}
Load - Prepares all sprites for drawing, called once.
void ISprite::Load(Shader spriteShader)
{
spriteShader.Use();
GLfloat vertices[] = {
//X Y Z
0.5f, -0.5f, 0.0f,
-0.5f, 0.5f, 0.0f,
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
0.5f, 0.5f, 0.0f,
-0.5f, 0.5f, 0.0f
};
glGenVertexArrays(1, &vertexArray);
glGenBuffers(1, &positionBuffer);
glGenBuffers(1, &texCoordsBuffer);
glGenBuffers(1, &colorBuffer);
glGenBuffers(1, &matrixBuffer);
glBindVertexArray(vertexArray);
//The vertex data will never change, so send that data now.
glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//For vertex Position
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(GLfloat), (GLvoid*)0);
//For texture coordinates
glBindBuffer(GL_ARRAY_BUFFER, texCoordsBuffer);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 2*sizeof(GLfloat), (GLvoid*)0);
//For Color
glBindBuffer(GL_ARRAY_BUFFER, colorBuffer);
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);
//For Transformation Matrix
glBindBuffer(GL_ARRAY_BUFFER, matrixBuffer);
for (int i = 0; i < 4; ++i)
{
glEnableVertexAttribArray(3 + i);
glVertexAttribPointer(3 + i, 4, GL_FLOAT, GL_FALSE,
4 * 4 * sizeof(GLfloat), (GLvoid*)(4 * i * sizeof(GLfloat)));
}
glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
glBindBuffer(GL_ARRAY_BUFFER, texCoordsBuffer);
glBindBuffer(GL_ARRAY_BUFFER, colorBuffer);
glBindBuffer(GL_ARRAY_BUFFER, matrixBuffer);
glBindVertexArray(0);
glVertexAttribDivisor(positionBuffer, 0);
glVertexAttribDivisor(texCoordsBuffer, 1);
glVertexAttribDivisor(colorBuffer, 1);
glVertexAttribDivisor(matrixBuffer, 1);
glVertexAttribDivisor(matrixBuffer + 1, 1);
glVertexAttribDivisor(matrixBuffer + 2, 1);
glVertexAttribDivisor(matrixBuffer + 3, 1);
ISprite::shader = &spriteShader;
}
Prepare Draw - called by each sprite, each frame. Sends data to static vectors
void ISprite::prepareDraw(void)
{
//Adds their personal data to vectors shared by class
glm::mat4 transform = calculateTransorm();
for (int i = 0; i < 4; ++i)
{
for (int j = 0; j < 4; ++j)
ISprite::transformMatrices.push_back(transform[i][j]);
}
texture.updateAnimation();
for (int i = 0; i < 12; ++i)
ISprite::textureCoordinatesAll.push_back(texture.textureCoordinates[i]);
ISprite::colorValues.push_back(color.x);
ISprite::colorValues.push_back(color.y);
ISprite::colorValues.push_back(color.z);
ISprite::colorValues.push_back(color.w);
}
Draw Sprites - called once each frame, actually draws the sprites
void ISprite::drawSprites(Texture testTexture)
{
shader->Use();
for (std::vector<ISprite*>::iterator it = Isprites.begin(); it != Isprites.end(); ++it)
(*it)->prepareDraw();
glBindVertexArray(vertexArray);
glBindTexture(GL_TEXTURE_2D, testTexture.ID);
//Bind texture here if you want textures to work. if not, a single texture atlas will be bound
glBindBuffer(GL_ARRAY_BUFFER, texCoordsBuffer);
glBufferData(GL_ARRAY_BUFFER, textureCoordinatesAll.size() * sizeof(GLfloat),
textureCoordinatesAll.data(), GL_STREAM_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, colorBuffer);
glBufferData(GL_ARRAY_BUFFER, colorValues.size() * sizeof(GLfloat),
colorValues.data(), GL_STREAM_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, matrixBuffer);
glBufferData(GL_ARRAY_BUFFER, transformMatrices.size() * sizeof(GLfloat),
transformMatrices.data(), GL_STREAM_DRAW);
glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 6, Isprites.size());
textureCoordinatesAll.clear();
colorValues.clear();
transformMatrices.clear();
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glBindVertexArray(0);
}
There could be a lot of reasons why nothing is rendered. Problems with the transformations, coordinates out of range, etc. But one thing related to instancing definitely looks wrong in the posted code:
glBindVertexArray(0);
glVertexAttribDivisor(positionBuffer, 0);
glVertexAttribDivisor(texCoordsBuffer, 1);
glVertexAttribDivisor(colorBuffer, 1);
...
The first argument to glVertexAttribDivisor() is the location of a vertex attribute, not the name of a buffer. Also, the state set by this call is part of the VAO state, so you should make these calls while the VAO is still bound.
So the calls should look like this:
glVertexAttribDivisor(0, 0);
glVertexAttribDivisor(1, 0);
glVertexAttribDivisor(2, 1);
...
glBindVertexArray(0);
where the first arguments to glVertexAttribDivisor() match the location values you also use as the first argument to glVertexAttribPointer() and glEnableVertexAttribArray().
The divisor value for the texture coordinates (attribute 1) should most likely be 0, since you want the texture coordinates to be set per vertex, just like the positions. For the colors and other remaining attributes, 1 is the correct value so that they are applied per instance.
Also, as I mentioned in a comment, you may also want to look into using point sprites. While they do not offer the same flexibility you can get from drawing individual quads, they can often be used for sprites. With point sprites, you only need one vertex per sprite, and the texture coordinates are generated automatically. My answer here gives an outline on how point sprites are used, including how to apply textures to them: Render large circular points in modern OpenGL.
I'm working on a rendering engine and so far it's been coming great, but I can not figure out why when I make two drawing calls to render different models, only 1 will show up.
I'm using wxWidgets to handle the window system, the code in question is pasted below. Any suggestions?
Main Rendering Loop
TestShader.Activate();
glUseProgram(TestShader.Program);
ProjectionMatrix = glm::perspective(45.0f, 4.0f / 3.0f, 0.1f, 100.0f);
int projectionMatrixLocation = glGetUniformLocation(TestShader.Program, "ProjectionMatrix");
glUniformMatrix4fv(projectionMatrixLocation, 1, GL_FALSE, glm::value_ptr(ProjectionMatrix));
glm::mat4 ViewMatrix = glm::lookAt(
glm::vec3(position),
glm::vec3(position+direction),
glm::vec3(up)
);
int viewMatrixLocation = glGetUniformLocation(TestShader.Program, "ViewMatrix");
glUniformMatrix4fv(viewMatrixLocation, 1, GL_FALSE, glm::value_ptr(ViewMatrix));
TestModel[1].Draw(TestShader, glm::vec3(0,0,-11));
TestModel[0].Draw(TestShader, glm::vec3(0,0,-1));
Refresh(false);
Model Drawing Function
void E_MODEL::Draw(EShader Shader, glm::vec3 Location)
{
if (!Registered) glGenVertexArrays(1, &VAO[0]);
glBindVertexArray(VAO[0]);
if (!Registered) glGenBuffers(1, &VBO[0]);
glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
if (!Registered) glBufferData(GL_ARRAY_BUFFER, Vertices.size() * sizeof(glm::vec3), &Vertices[0], GL_STATIC_DRAW);
if (!Registered) glGenBuffers(1, &VBO[1]);
glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
if (!Registered) glBufferData(GL_ARRAY_BUFFER, Normals.size() * sizeof(glm::vec3), &Normals[0], GL_STATIC_DRAW);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glm::mat4 modelMatrix = glm::translate(glm::mat4(1.0f), Location);
int modelMatrixLocation = glGetUniformLocation(Shader.Program, "modelMatrix");
glUniformMatrix4fv(modelMatrixLocation, 1, GL_FALSE, glm::value_ptr(modelMatrix));
glDrawArrays( GL_TRIANGLES, 0, Vertices.size() );
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
Registered = true;
}
Vertex Shader
#version 330 core
// Input vertex data, different for all executions of this shader.
layout(location = 0) in vec3 vertexPosition_modelspace;
layout(location = 1) in vec3 vertexColor;
// Output data ; will be interpolated for each fragment.
out vec3 fragmentColor;
// Values that stay constant for the whole mesh.
uniform mat4 ProjectionMatrix;
uniform mat4 ViewMatrix;
uniform mat4 modelMatrix;
void main(){
gl_Position = ProjectionMatrix * ViewMatrix * modelMatrix * vec4(vertexPosition_modelspace,1);
// The color of each vertex will be interpolated
// to produce the color of each fragment
fragmentColor = vertexColor;
}
Fragment Shader
#version 330 core
// Interpolated values from the vertex shaders
in vec3 fragmentColor;
// Ouput data
out vec3 color;
void main(){
// Output color = color specified in the vertex shader,
// interpolated between all 3 surrounding vertices
color = fragmentColor;
}
glClear clears a buffer. With the GL_COLOR_BUFFER_BIT flag, you are clearing the color buffer. With the GL_DEPTH_BUFFER_BIT flag, you are clearing the depth buffer. By doing this each time you draw a model, the color and depth information written previously is cleared. This means you are erasing the image every time you draw a model.
You typically clear the buffers once per "paint" or "present". That is, you clear once, you draw N times, you present once. What you are doing now is clear, draw, clear, draw... present.
TL;DR: Call glClear once, before all of your drawing, not before each draw.
is it the glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); inside the draw function? maybe move that out to before you make the calls the draw functions?