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POParticle trails OpenGL 3.3, glClear?
 

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  1. POParticle trails OpenGL 3.3, glClear?
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    <p>I'm an OpenGL newbie. I'm trying to create a system of particles and I have everything set up, but the particle trails.</p> <p>The easiest way, that I see, for me to implement this is to clear the screen with a nearly transparent colour e.g alpha = 0.05. This will fade the previous positions drawn.</p> <p>However, this doesn't work. I've also tried to draw a rectangle over the screen.</p> <p>After setting alpha of my particles to 0.3, my transparency doesn't seem to be working.</p> <p>This is my code:</p> <pre><code>do{ glBindVertexArray(VertexArrayID); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); time = (float)glfwGetTime(); // ** Calculating new positions and placing into vertex array iter = 0; for(int i = 0; i &lt; n; i++){ bodies[i].F(bodies, i, n, 1); bodies[i].calcPosition(dt); bodies[i].getVertexArray(vertexArray, iter, scale, i); } for(int i = 0; i &lt; n; i++){ bodies[i].F(bodies, i, n, 2); bodies[i].calcVelocity(dt); } // ** glBufferData(GL_ARRAY_BUFFER, 21 * 6 * n * sizeof(float), vertexArray, GL_STREAM_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, 20 * 3 * n * sizeof(GLuint), elements, GL_STREAM_DRAW); glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glVertexAttribPointer( 0, 2, GL_FLOAT, GL_FALSE, 6*sizeof(float), (void*)0 ); glEnableVertexAttribArray(1); glVertexAttribPointer( 1, 4, GL_FLOAT, GL_FALSE, 6*sizeof(float), (void*)(2*sizeof(float)) ); glDrawElements(GL_TRIANGLES, 20 * 3 * n, GL_UNSIGNED_INT, 0); glDisableVertexAttribArray(0); glDisableVertexAttribArray(1); glfwSwapBuffers(); while((float)glfwGetTime() - time &lt; dt){ } } // Check if the ESC key was pressed or the window was closed while( glfwGetKey( GLFW_KEY_ESC ) != GLFW_PRESS &amp;&amp; glfwGetWindowParam( GLFW_OPENED ) ); </code></pre> <p>My shaders:</p> <pre><code>#version 330 core in vec4 Color; out vec4 outColor; void main() { outColor = Color; } #version 330 core layout(location = 0) in vec2 position; layout(location = 1) in vec4 color; out vec4 Color; void main(){ gl_Position = vec4(position, 0.0, 1.0); Color = color; } </code></pre> <p>This outputs n circles (20 sided polygons) travelling round the screen in different colours. All previous drawings stay on the screen, I want them to fade</p> <p>Thanks Andy</p>
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    1. USAndrew Seymour
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