Real-Time Physics Simulation Forum

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//// Helper class; draws the world as seen by Bullet.
//// This is very handy to see it Bullet's world matches yours.
//// This example uses the old OpenGL API for simplicity, 
//// so you'll have to remplace GLFW_OPENGL_CORE_PROFILE by
//// GLFW_OPENGL_COMPAT_PROFILE in glfwWindowHint()
//// How to use this class :
//// Declare an instance of the class :
//// BulletDebugDrawer_DeprecatedOpenGL mydebugdrawer;
//// dynamicsWorld->setDebugDrawer(&mydebugdrawer);
//// Each frame, call it :
//// mydebugdrawer.SetMatrices(ViewMatrix, ProjectionMatrix);
//// dynamicsWorld->debugDrawWorld();
//
//class BulletDebugDrawer_DeprecatedOpenGL : public btIDebugDraw{
//public:
//	void SetMatrices(glm::mat4 pViewMatrix, glm::mat4 pProjectionMatrix){
//		glUseProgram(0); // Use Fixed-function pipeline (no shaders)
//		glMatrixMode(GL_MODELVIEW);
//		glLoadMatrixf(&pViewMatrix[0][0]);
//		glMatrixMode(GL_PROJECTION);
//		glLoadMatrixf(&pProjectionMatrix[0][0]);
//	}
//	virtual void drawLine(const btVector3& from,const btVector3& to,const btVector3& color){
//		glColor3f(color.x(), color.y(), color.z());
//		glBegin(GL_LINES);
//			glVertex3f(from.x(), from.y(), from.z());
//			glVertex3f(to.x(), to.y(), to.z());
//		glEnd();
//	}
//	virtual void drawContactPoint(const btVector3 &,const btVector3 &,btScalar,int,const btVector3 &){}
//	virtual void reportErrorWarning(const char *){}
//	virtual void draw3dText(const btVector3 &,const char *){}
//	virtual void setDebugMode(int p){
//		m = p;
//	}
//	int getDebugMode(void) const {return 3;}
//	int m;
//};

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// Helper class; draws the world as seen by Bullet.
// This is very handy to see it Bullet's world matches yours
// How to use this class :
// Declare an instance of the class :
// 
// dynamicsWorld->setDebugDrawer(&mydebugdrawer);
// Each frame, call it :
// mydebugdrawer.SetMatrices(ViewMatrix, ProjectionMatrix);
// dynamicsWorld->debugDrawWorld();
GLuint VBO, VAO;
class BulletDebugDrawer_OpenGL : public btIDebugDraw {
public:
	void SetMatrices(glm::mat4 pViewMatrix, glm::mat4 pProjectionMatrix) 
	{
		glUniformMatrix4fv(glGetUniformLocation(lineShader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(pProjectionMatrix));
		glUniformMatrix4fv(glGetUniformLocation(lineShader.Program, "view"), 1, GL_FALSE, glm::value_ptr(pViewMatrix));
	}

	virtual void drawLine(const btVector3& from, const btVector3& to, const btVector3& color) 
	{
		// Vertex data
		GLfloat points[12];

		points[0] = from.x();
		points[1] = from.y();
		points[2] = from.z();
		points[3] = color.x();
		points[4] = color.y();
		points[5] = color.z();

		points[6] = to.x();
		points[7] = to.y();
		points[8] = to.z();
		points[9] = color.x();
		points[10] = color.y();
		points[11] = color.z();

		glDeleteBuffers(1, &VBO);
		glDeleteVertexArrays(1, &VAO);
		glGenBuffers(1, &VBO);
		glGenVertexArrays(1, &VAO);
		glBindVertexArray(VAO);
		glBindBuffer(GL_ARRAY_BUFFER, VBO);
		glBufferData(GL_ARRAY_BUFFER, sizeof(points), &points, GL_STATIC_DRAW);
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), 0);
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
		glBindVertexArray(0);

		glBindVertexArray(VAO);
		glDrawArrays(GL_LINES, 0, 2);
		glBindVertexArray(0);

	}
	virtual void drawContactPoint(const btVector3 &, const btVector3 &, btScalar, int, const btVector3 &) {}
	virtual void reportErrorWarning(const char *) {}
	virtual void draw3dText(const btVector3 &, const char *) {}
	virtual void setDebugMode(int p) {
		m = p;
	}
	int getDebugMode(void) const { return 3; }
	int m;
};

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#version 330 core
in vec3 fColor;
out vec4 color;

void main()
{
    color = color;   
}

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#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;

out VS_OUT {
    vec3 color;
} vs_out;

uniform mat4 projection;
uniform mat4 view;

void main()
{
    gl_Position = projection * view * vec4(position, 1.0f);

    vs_out.color = color;
}

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public:
	struct 
	{
		btVector3 p1;
		btVector3 p2;
			
	} typedef LineValues;


void PhysicsDraw::drawLine(const btVector3 &from,
	const btVector3 &to,
	const btVector3 &color)
{
	// draws a simple line of pixels between points but stores them for later draw
	LineValues Line;
	Line.p1 = from;
	Line.p2 = to;

	TheLines.push_back(Line);

// we don't care about colour?		
}

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void PhysicsDraw::DoDebugDraw()
{// set up the line shader and then draw the buffer
	

	
			//load the vertex data info
		glVertexAttribPointer(this->positionLoc,  // the handle for the a_position shader attrib
			3,	// there are 3 values xyz
			GL_FLOAT, // they a float
			GL_FALSE, // don't need to be normalised
			4*sizeof(float),  // how many floats to the next one(be aware btVector3 uses 4 floats)
			(GLfloat*)&this->TheLines[0]  // where do they start as an index); // use 3 values, but add stride each time to get to the next
		);
	
		glEnableVertexAttribArray(this->positionLoc);
		glDrawArrays(GL_LINES, 0, TheLines.size()*2);
	
		
	TheLines.clear();
	
}

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	DynamicPhysicsWorld->debugDrawWorld();
	
	glm::mat4* Projection = TheCamera->GetProjection(); 
	glm::mat4* View = TheCamera->GetView();
	glUseProgram(PhysicsDraw::ProgramObject);
	GLint MatrixID =	glGetUniformLocation(PhysicsDraw::ProgramObject, "MVP"); // use the MVP in the simple shader
	// make the View and  Projection matrix
	glm::mat4 VP        = *Projection * *View;  // Remember order seems backwards
	glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &VP[0][0]);
	
	this->m_pPhysicsDrawer->DoDebugDraw();

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#version 100
// very simple and probably only used for debug systems
attribute vec3 a_position;
uniform mat4 MVP; 
void main()
{
	gl_Position = MVP*vec4(a_position, 1);

}
and the frag


	#version 100
	// very simple and probably likely to never be needed

precision mediump float;

void main()
{
	gl_FragColor= vec4(1.0, 1.0, 0.0, 1.0); // show a plain colour

}